Parasitic wasps lay their eggs directly into the eggs of various host

My pick : A

A. The size of the smallest host egg that a wasp could theoretically parasitize can bedetermined from the wasps egg-laying behavior.

since the wasps somehow know how many eggs to lay in order for their larvae to survive, one can in theory compute the smallest size based on their egg-lay behavior ..

As you can see below - all the other choices can be eliminated with lot more certainity, leaving just "A"
B. Host insects lack any effective defenses against the form of predation practiced byparasitic wasps.

lack of effective defensive mechanism in the host - is out of scope

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of differenthost species.
nothing in the argument talks about how the wasps know how many eggs to lay - hence out of scope

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae morequickly than would laying too many eggs.

- the argument is not about which method will lead to the quicker end of the wasp larvae - so we cannot come to this conclusion that one method will lead to quick death than the other

E. Parasitic wasps use visual clues to calculate the size of a host egg.
- again, how the wasps know how many eggs to lay is out of scope

can anyone please explain it?
The passage always talks about no of eggs then why we are taking "size" in consideration?

Can't understand why B is not the right answer. From the statements we can clearly see that the survival rate of the eggs depends purely on the # of eggs laid.
Someone please explain.
I understand you can eliminate A as well....
Stuck btw A & B

That's right.

(A) is making a claim that there is a connection between size of host egg to be parasitized and wasp's egg laying behavior. And we have information to support that in the passage.

Laying a lot of eggs means the size of parasitized host egg must be large. Laying few eggs means size of parasitized host egg must be small.

We basically were able to find a conclusion that could be drawn from the passage - this is the same as an inference question, just rephrased in a different way. With inference questions, we have to find an answer choice that is the "argument/conclusion" and then find information in the passage that would support and make that "argument/conclusion" valid.

What we learn about the parasitic wasp is that it knows exactly how many eggs to lay depending on the size of the host egg. Therefore, if the wasp lays x number of eggs we know that it will correspond to a certain size of host egg. From this information, we can figure out the largest sized host egg a wasp could parasitize and the smallest host egg it could parasitize. In the case of smallest egg, it would lay only a limited number of eggs. Regardless of that number, it's egg laying behavior, i.e., how many eggs it lays, will give indicate the size of the host egg.

Thus the answer is (A).

The passage talks about the size of the HOST EGG. The wasp lays its own eggs INSIDE a HOST EGG (someone else's egg). How many eggs should it lay depends on the SIZE of the host egg. Say, if the HOST egg is large, it will lay 20 eggs inside it and if the host egg is small, it will lay 10 eggs inside it etc.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.

We cannot conclude (B) from the argument. Host insects may have some effective defines. Perhaps, they are able to defend their eggs 8 out of 10 times - we don't know. The argument only tells us how the parasitic wasps lay their eggs whenever they are able to.

On the other hand, we can conclude (A)
A. The size of the smallest host egg that a wasp could theoritically parasitize can be determined from the wasp's egg- laying behavior.
Wasp's egg laying behaviour depends on the size of the host egg. Smaller the host egg, fewer eggs the wasp lays. So theoretically, seeing how it lays fewer and fewer eggs in smaller and smaller host eggs, we can find the size of the host egg in which it can lay only one egg.

I don't understand how A can be correct, besides using process of elimination. The passage tells us that wasps lay eggs directly into the host egg in exactly the right amount. "A" says that we can figure out the smallest host egg a wasp can theoretically parasitize based on their egg-laying behavior. However, we know that their egg-laying behavior is dependent on the size of the host egg. Therefore wouldn't their egg-laying behavior change for each size of host egg? If that's the case, how could someone use their egg-laying behavior, which is constantly changing, to figure out anything?

Also, How the size can be determined from behavior?! in the passage we see they just know( based on instinct or experience, we don't know) but I cannot find correlation between choice A and passage
could you explain it, please?

The egg laying behaviour has a pattern.
For a small egg (say 3 cm inside radius assuming spherical egg), the wasp lays few eggs, say 2.
For a larger egg (say 5 cm inside radius assuming spherical egg), the wasp would lay more eggs, say 5.
For an even larger egg (say 8 cm inside radius assuming spherical egg), the wasp would lay even more eggs, say 10.
and so on...

Wasps follow this pattern. Extrapolating it, we can theoretically find the size of the smallest egg that a wasp could parasitise.



The argument tells us - "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg"
So if the host egg is large in size, the wasp lays more eggs in it, but if it is smaller in size, the wasp lays fewer eggs inside it.
By observing their behaviour (how many eggs in which size host egg), we can extrapolate to find the size in which the wasp will, theoretically, lay only 1 egg. So any smaller than that and the wasp would lay no egg in it.

GMATNinja VeritasKarishma

Stmt: Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

The statement says wasps lay the exact right number of eggs for any suitable size of host egg, and says "If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae." How else would they know whether they were laying the exact right amount or whether they were laying too many or too few eggs if they didn't learn this, such as by learning from experience as answer choice C states? I understand the answer choice adds a bit of information, but how is that answer choice not something that can be easily inferred from the statement?

Is there a more general rule for these conclusion-type CR questions that I can use to help eliminate these types of answer choices in future questions? I seem to miss questions with similar answer choices to this one too often.

You need to consider if alternatives are possible. By saying that they learn from experience, you are saying that initially, they lay too many eggs and learn. Then sometimes they lay too few eggs and learn. Finally, after a few losses they get it right.
But we don't know that this happens. What if their instincts told them how many to lay based on the egg size. That they can eyeball it and they just know what to do. That they do it right from the beginning.
Animals have instincts, right? e.g. they know they have to defend themselves against predators. This is how they have evolved in nature.
So whether they learned from experience or intuition or were taught by their parents, we don't know. Hence (C) is unwarranted.

The first sentence of the passage tells us what happens (the parasitic wasps lay their eggs in exactly the right numbers for any suitable size of host egg), but it doesn't tell us how that phenomenon happens.

Is this something the wasps learn from experience? Something the wasps instinctively know to do? Something that happens because the wasps have a specialized organ that measures the size of the host eggs? Something the adult wasps read about in a parasitic-wasp parenting book??

The passage doesn't give us any clues regarding the mechanism of the phenomenon. Sure, (C) could be true, but there is no evidence in the passage indicating that learning from experience is the precise mechanism. So (C) is out.

I hope that helps!

(A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.

(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps. - We cant tell this from the argument. Maybe / Maybe not

(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species. - maybe the first time itself they did why experience probably its an intuitive thing

(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs. - cant be determined

(E) Parasitic wasps use visual clues to calculate the size of a host egg. - maybe can use touch sensors

In the Inferencing question, what will be true is either the logical deduction from the statements or the rephrasing of the premise. Any outside information is wrong.

Which of the following conclusions can properly be drawn from the information above?

(A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior. - ok, Can we logically deduce? Yes.

(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps. - Why the host allows it. Is it in the premise? No. Out of scope.

(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species. - How they learn. It might be true but is it mentioned in the premises. No.

(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs. - Distortion. We don't know.

(E) Parasitic wasps use visual clues to calculate the size of a host egg. - Might be but is it mentioned in the premises. No.