This does not help explain the puzzling fact. (A) says that modern tree-dwelling kangaroos must descend tree trunks more slowly than their ancestors, presumably because they lack opposable thumbs, without explaining why they lost this trait.

This does not help explain the puzzling fact. (B) discusses size, which is not one of the traits the stimulus discusses as being beneficial for a tree-dwelling lifestyle. Furthermore, (B) offers a difference between land- and tree- dwelling kangaroos, not a similarity.

(C) offers a difference between land- and tree- dwelling kangaroos, not a similarity. The difference in length and flexibility of the kangaroos’ tails is not helpful for explaining the puzzling fact in the stimulus.

(D) says modern land- and tree-dwelling kangaroos share a similarity: in addition to sharing a common ancestor, they both evolved from land-dwelling kangaroos. This explains why modern tree-dwelling kangaroos lost some of their earlier ancestor’s beneficial tree-dwelling traits.

(E) offers a difference between land- and tree- dwelling kangaroos, not a similarity. The difference in the size and strength of the kangaroos’ hind legs is not helpful for explaining the puzzling fact in the stimulus.