Biology

The correct answer is: C. C and D.

In a phylogenetic tree, to determine the closeness of the relationship between two extant species, the key is to look at how recent their common ancestor is, that is, the position of the branching point (node).

A and B: They come from different branches, and the node corresponding to their common ancestor is relatively low, which means that the common ancestor dates back a long time, so the relationship is not close.

B and C: Although there is a common - ancestor node 2, compared with C and D, the common ancestor is not the most recent.