Let's look at the structure of the argument: (1) The more genetically similar two species are, the more recently they diverged. (2) Bears & raccoons diverged 30 to 50 million years ago. (3) Red pandas & raccoons/ coatis diverged a few million years later (4) 10 million years later giant pandas diverged from the other bears.
In other words, if we were to rank when species separated, we would come up with the following chain:
bears & racoons > red pandas & racoons/ coatis > giant pandas & other bears
Since the argument equates genetic similarity with the date of divergence, we can conclude that bears & raccoons are most genetically dissimilar and giant pandas & other bears are most genetically similar among the species discussed.
Let's look at the answer choices:
(A) Giant pandas and red pandas are more closely related than scientists originally thought they were
Incorrect. The argument never tells us what the scientists' original theory was or about the genetic similarity between giant pandas and red pandas.
(B) Scientists now count the giant panda as the eight species of a bear.
Incorrect. Nowhere does the argument suggests that the scientists changed the classification of any species based on the presented findings.
(C) It is possible to determine, within a margin of just a few years, the timing of divergence of various species.
Incorrect. The argument gives us ranges of a few MILLION years, we cannot infer that it is possible to determine the timing within a margin of a few years.
(D) Scientists have found that giant pandas are more similar genetically to bears & raccoons.
Correct. If you look at our chain above, you can see the bears & raccoons diverged millions of years before giant pandas & other bears, thus we can conclude that they are more genetically similar to other bears than to raccoons.
(E) There is a substantial consensus among scientists that giant pandas and red pandas are equally related to raccoons.
Incorrect. The argument only tells us when red pandas diverged from the ancestor of today's raccoons, we have no information about the giant pandas versus red pandas in that regard. Also, we could never infer a substantial consensus from arguably the findings of one study as in this stimulus.
Let me know if this makes sense and if you have any other questions.
