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Premise: Early mammals spent time in low light levels. So mammals today are naturally adapted to dim lighting.
Conclusion: Regular exposure to bright artificial light interferes with sleep cycles.
Logical gap: The premise is about dim natural light and argument drags this to conclude about bright artificial light interfering with sleep cycles.

Evaluating answer choices

A) This is a statement that follows from the argument if the conclusion is true. But this need not be true for conclusion to hold good. We just need a possibility of sleep interference due to bright lights. The conclusion will not break if this statement is not true.
B) This is a weakener. If artificial light behaves differently than natural light, then conclusion is weakened
C) This needs to be true and hence is an assumption The sleep cycles should be dependent atleast in part on the light conditions to which mammals are adapted. If this is not true (negating to see if conclusion breaks), the sleep cycles are independent on the light conditions. This breaks the correlation between light conditions and sleep in the conclusion.
D) We are not concerned about the quality of sleep cycles in early and modern day mammals. This is irrelevant
E) Although this is a strengthener, negating this will not break the conclusion about the sleep cycles. Moreover, the premise specifies about low natural light environments where early mammals stayed like forests and burrows.

Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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Assumption

Conclusion: Regular exposure to artificial bright lights likely interferes with maintaining proper sleep cycle.

Premise: Early mammals spent most of their time in dim light environments & hence they've adapted to the dim lights.

Assumption (holding link): To be found.

Answer: E .

Reason: For the bright lights to interfere the sleep cycle, intensity must be atleast some units greater than dim lights (natural lights).

Not the answer & reason:

B. Too broad - it's just stating "artificial lights affect in different way" -- what way? Does it have something to do with sleep cycle? We don't know.

C. Same reason as before - "Sleep cycle depends atleast in part on environmental conditions" -- what condition? Anything with light? Don't really know.
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A: Nowhere are we quantifying the number of irregular sleep cycles. more or less does not matter. OOS
B: Nowhere is it said that sleep cycle is linked to effect on brain. OOS
C: Negating C weakens the conclusion. If Mammals are not dependent on what they naturally adapted to, their sleep cycles will not be impacted by bright lights. CORRECT
D: Irrelevant. OOS
E: Irrelevant. OOS
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IMO Answer should be C.

A. It talks about mammals in general and not mammals in today. Eliminate
B. Exposure affects the brain but doesn't connect brain to sleep cycle. It doesn't fill the gap completely.
C. Bingo! It connects all the dots since modern mammals should be adapted by their environment and is a partial factor
D. Irrelevant as this doesn't connect the dot of artificial light and sleep cycle
E. Irrelevant as the conclusion is not about the intensity
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The main conclusion of the argument is Regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles. Let's check options one my one to identify assumptions:

(A) It is not an Assumption since more or less irregular sleeping cycles comparison is not necessary. We need to establish a relationship between sleeping cycle and adaptive conditions. From argument it seems adaptive conditions are natural Dim Lighting.
(B) It is not an assumption since nothing is mentioned about the functionality of the brain in relation with lightening.
(C) It is an Assumption. Carefully we can observe that it is establishing today's mammal's sleeping cycle relationship with naturally adaptive environmental conditions using modifier atleast. If this is true then it becomes necessary condition and other environmental conditions can interfere sleeping cycle.
(D) It is not an assumption since Healthy/bad sleeping cycle comparison is not necessary.
(E) Intensity of light comparison is not necessary and hence it's not an assumption.
Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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Premises:
- Early mammals didn't have a factor (bright artificial light)
- Modern mammals are by nature adapted to not having that factor
- But Modern mammals are facing this factor (bright artificial light)
Conclusion:
In Modern mammals will have sleep cycle disturbances (because of the factor)


Gap:
Premise talks about early vs modern mammals having the factor. Conclusion talks about something else called sleep cycle.
So they must be assuming that having the factor -> sleep cycle disturbance.

A. This statement is saying that: If the mammal has more of the factor -> then it should have more of the disturbance. But that condition is not needed for the conclusion. Even if the ones with more light has same disturbance, the conclusion stands where it is.
B. This is talking about artificial light vs natural light -> and it just says different. Whether it is different or not is not a necessary condition for conclusion.
C. Correct. Author must be assuming that the factor can cause the disturbance
D. It is possible that early mammals may not have had good sleep cycle due to other issues say for ex: sounds, hunting by predators, or insect bites etc. But the argument is not about that. The factor mentioned is different between early and modern mammals -> therefore this factor will contribute to sleep cycle disturbance
E. Whether bright light intensity exceeds or not that of the natural daylight, the argument that the difference in the factor exists and that can lead to sleep cycle disturbance.
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Biologist states that early mammals spent most of their team in low light environments. - > Mammals today are naturally adapted to dim lighting.

Conclusion: - Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

There should be some correlation between lighting / environmental conditions and sleep cycles of mammals for the conclusion to hold true.

A. This is similar to the conclusion itself. Incorrect
B. There is unnecessary comparison between exposure to artificial light vs natural light. Incorrect
C. If the statement is negated, the conclusion falls apart. If the sleep cycles don't depend on environmental conditions to which mammals are naturally adapted including lighting conditions then the conclusion can not hold true. Correct
D. This statement has no relation with lighting conditions in past and today and is unrelated to the conclusion. Incorrect
E. There is an unnecessary comparison between bright artificial light and daylight. Incorrect

IMO C
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The biologist's argument is that early mammals lived in dim environments modern mammals are also adapted to it therefore regular exposure to bright artificial light likely interferes with proper sleep cycles.
C is correct because it if sleep cycles didn't depend on light adaption, bright light wouldn't matter.
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Immediately, there appears to be a logical leap here. Mammals have adapted to dim lighting -> [an unstated assumption] -> Exposure to bright light will interfere with their sleep cycles.

What fits the best here? We can just take this statement and try to fit in the options and see which one reveals the assumption.


A. Mammals have adapted to dim lighting -> Mammals that spend most of their time in brightly lit environments tend to have irregular sleep cycles -> exposure to bright artificial light will interfere with their sleep cycle.

Yes, but then again, the jump from Mammals adapting to dim lighting to their response to brightly lit environments isn't stated. We haven't established that dim lighting adaptation equals bright artificial lighting maladaptation.

B. Mammals have adapted to dim lighting -> Exposure to artificial light affects the brain differently than exposure to natural light -> Exposure to bright artificial light will interfere with sleep cycles.

This doesn't really add any value. Differently means anything, and the comparison isn't between artificial and natural light.

C. Mammals have adapted to dim lighting -> Modern mammals' sleep cycles depend at least in part on the environmental conditions to which mammals are naturally adapted -> Exposure to bright artificial light will interfere with their sleep cycle.

This looks good, mainly because the fact that mammals have adapted to dim lighting or, the fact that adaptation to environmental conditions has a role to play in something, explains why exposure to bright light will interfere with their sleep cycles (as mammals aren't naturalized to bright light).

D. Mammals have adapted to dim lighting -> Early mammals had healthier sleep cycles than today's mammals -> Exposure to bright artificial light will interfere with sleep cycles.

This assumption doesn't do anything. We're talking about modern mammals and their relationship with bright lights and sleep cycles, not their comparison with their ancestors.

E. Mammals have adapted to dim lighting -> Bright artificial lights typically exceed the intensity of daylight in natural environments -> Exposure to bright artificial light will interfere with sleep cycles.

Again, there comparison isn't between bright artificial lights and natural lights. Hence, eliminate.

So C, IMO, is the most probable answer.




Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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Conclusion : Regular exposure to bright artificial light interferes with proper sleep cycles.
Assumption : Evolutionary adoption to Modern sleep disruption
Choice A : About Mammals in bright environments not required - Irrelevant comparison.
Choice B : Artificial vs Natural light brain effects - Too specific .
Choice C : Missing link , If this falls conclusion will collapse.✅
Choice D : Health of early Mammal's sleep - Historical , Not Required .
Choice E : Artificial light stronger than daylight - Unnecessary extreme statement.
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Answer-C, as the para is getting linked to early mammals.
Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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On analyzing the options,

(A) Not required because the argument does not rely on observed sleep problems in currently light-exposed mammals. Eliminate
(B) This is irrelevant to the conclusion because we are not concerned with whether light is artificial or natural. Eliminate
(C) This is a necessary assumption because the conclusion only follows if modern mammals’ sleep cycles are influenced by conditions they are evolutionarily adapted to. Keep
(D) Irrelevant to the argument as the argument does not compare the quality of early and modern sleep cycles.Eliminate
(E) Not a necessary assumption as interference could occur even if artificial light is not brighter than natural daylight. Eliminate

The correct answer is hence option (C)
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(A) True. This is the necessary statement to conclude that exposed to bright artificial light can interfere with proper sleep cycles.
(B) The brain is not relevant.
(C) The term "at least" is not strong enough.
(D) This is not the necessary assumption to conclude regular exposure to bright 'artificial' light cause some troubles with sleep cycles.
(E) The intensity of daylight is not relevant.
Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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I think option A should be correct as it directly supports the conclusion of the paragraph.
Exposure to Bright light->Irregular Sleep cycles.
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Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles. (The argument does not need this comparison, and it only talk about mammals that live in bright lit environment tend to have irregular sleep cycles) Irrelevant
(B) Exposure to artificial light affects the brain differently than exposure to natural light. (It doesn't matter to the argument how the light affects the brain) Wrong
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted. (If sleep cycles were not influenced by environmental adaptation, then early mammals living in dim light would not matter. This is a necessary assumption for argument to hold. And negation of this option also weakens the conclusion) Correct

(D) Early mammals had healthier sleep cycles than most mammals have today. (The argument is only about the interference and not this) Wrong
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments. (Intensity doesn't matter for the argument to hold) Wrong

C
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The author says: mammals are adapted to dim lighting -> their sleep cycles will be hindered by bright artificial light exposure.

The connections the author has to make to arrive at the conclusion are the following:
  • the fact that you're adapted to one thing prevents you from being also adapted to another (namely, you can't be adapted both to dim light and to bright one).

  • the light you're naturally adapted to has impact on your sleep cycles.

Now let's find one of these assumptions in the answer options.

A) Not bad, but it's not a must for the argument. What about mammals who just spend a lot but not 'most' of their time in lit places? And how much more irregular cycles are, significantly or not?
B) Perhaps it does, but while the context may be misleading into comparing natural to artificial lights, the author only actually focuses on bright/dim, so this is irrelevant.
C) Hits the nail on the head, since there's a mandatory connection between light and sleep for the conclusion to work.
D) Not necessary at all, since there are so many factors that could have equally impacted the sleep quality.
E) Artificial lights are brighter, okay; but don't we already know it from comparing dim and bright lights in the very argument? Seems excessive.

Therefore, the right answer is C.
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Bunuel
Biologist: Early mammals spent most of their time in environments with low light levels, such as forests and burrows. As a result, mammals today are naturally adapted to dim lighting. Hence, regular exposure to bright artificial light is likely to interfere with maintaining proper sleep cycles.

Which of the following is an assumption the biologist’s argument requires?

(A) Mammals that spend most of their time in brightly lit environments tend to have more irregular sleep cycles.
(B) Exposure to artificial light affects the brain differently than exposure to natural light.
(C) Modern mammals’ sleep cycles depend at least in part on environmental conditions to which mammals are naturally adapted.
(D) Early mammals had healthier sleep cycles than most mammals have today.
(E) Bright artificial light typically exceeds the intensity of daylight in natural environments.

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Assumption question - Must be needed by the argument
A -> This is a tending to a conclusion for the argument.
B -> Effect on brain is not discussed
C -> Correct. This dependency needs to exist for the argument to stand
D -> No comparison if required as an assumption
E -> Irrelevant comparison

Option C
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