Easy A!

D, E - they are clearly out of scope
B - too narrow in scope. It talks only about 'certain extinctions'.
C - Ok. we know why 'Some species' became extince. What about the others? Again, too narrow in scope.

The answer should be A:

A. This answer choice gives us a reason that explains how extinction can occur suddenly with many species going extinct.

B. This answer choice gives an explanation for the extinction of a few species.

C. This answer choice explain only how "some species" become extinct.

D. We are only concerned about the times that have "fossil records."

E. We are not concerned about how species are least likely to become extinct.

I think because the question asks: Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
_________________

Can any one give a power-score cr bible explanation for this paradox question ?

Extinction is a process that can depend on a variety of ecological, geographical, and
physiological variables. These variables affect different species of organisms in different
ways, and should, therefore, yield a random pattern of extinctions. However, the fossil
record shows that extinction occurs in a surprisingly definite pattern, with many species
vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the
patterned extinctions revealed by the fossil record?

A. Major episodes of extinction can result from widespread environmental disturbances thataffect numerous different species.

B. Certain extinction episodes selectively affect organisms with particular sets ofcharacteristics unique to their species.

C. Some species become extinct because of accumulated gradual changes in their localenvironments.

D. In geologically recent times, for which there is no fossil record, human intervention haschanged the pattern of extinctions.

E. Species that are widely dispersed are the least likely to become extinct

Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.

Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?

QUESTION TYPE:
Explain – We need to find an answer that resolves the mystery.

FACTS:
1) Extinctions should be random because various factors should affect species randomly
2) Extinctions are NOT random---they happen in clusters, wiping out many species at once

GOAL:
Find an answer that explains how despite random factors, many species are wiped out in big clusters at once

A. Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
Yes! Think asteroid, or mega-volcano. There’s some sort event that takes down swathes of species.

B. Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
This contradicts the second fact. Don’t we know that many species are wiped out at once? So this answer that species with particular characteristics are selectively wiped out would intensify the mystery.

C. Some species become extinct because of accumulated gradual changes in their local environments.
This answer only addresses specific single species extinctions, AND that they happen gradually over time. That makes this answer wrong for two reasons. A gradual extinction affecting some species is not the type of extinction the question deals with.

D. In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
This answer flat out announces that it addresses circumstances separate from those in the prompt. Boot it.

E. Species that are widely dispersed are the least likely to become extinct
This is an interesting fact, but it’s completely off-topic. Does the fact that species that are widely dispersed are least likely to become extinct at all reconcile how species go extinct in clusters? No. Its gone too.

A is our answer.
_________________

Argument Construction

Situation The fossil record reveals that species become extinct in a surprisingly definite pattern, with multiple species vanishing simultaneously.
Reasoning Which point provides a basis for explaining the pattern? The passage states that the process of extinction depends on so many variables—in the ecology and geography of the environment and in the physiology of the species—that the expected outcome would be a random pattern of extinctions. Yet a definite pattern is found instead. What could explain the disappearance of multiple species at the same time? If there were significant widespread changes in the environment, multiple species could be affected simultaneously, causing their extinction.

A Correct. This statement properly identifies a basis for explaining the pattern of many species becoming
extinct simultaneously.

B This explanation of selective extinction does not explain how many species become extinct at the same
time.

C This explanation addresses only some species, not many species.

D The passage is based on what the fossil record suggests; more recent times, having no fossil record, are outside the consideration of the passage.

E Indicating which species are least likely to become extinct does not explain a pattern of simultaneous extinction of many species.

The correct answer is A.
_________________

As this is a CR question, let’s begin by reading the Question Stem: this question is EXPLAIN THE ARGUMENT question


Premise:
1. Extinction  Depends  ecological, geographical and physiological variables
2. Variables affect different species  different ways  Hence, should yield random pattern of extinctions
3. However  Fossil record shows  extinction occurs in a surprisingly definite pattern  MANY species vanishing at the same time

We need to look for option which can provide us with a reason where one or multiple variables impact multiple species at the same time.

(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
- This looks the correct answer, it is telling us that widespread environmental disturbances have affected different species (One variable impacting multiple species). Lets read other options as well. (A is the CORRECT answer)

(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
- Problem with this is it is referring to a specific species and not multiple, hence this does not explain what we are looking for

(C) Some species become extinct because of accumulated gradual changes in their local environments.
- Again referring to some species not necessarily multiple species

(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
- We are not talking about any recent times in this passage neither specifically about human interventions

(E) Species that are widely dispersed are the least likely to become extinct
- This goes against of what we are looking for

_________________

Imo A
We have to look for some reason which caused definite extinction pattern of different species .
Option A provides that some natural calamity can affect several species simultaneously.
_________________