The Following Questions Refer to the Evolutionary Tree Shown Below

The following questions refer to the evolutionary tree shown below.
The horizontal axis of the cladogram depicted below is a timeline that extends from? 100 000 years ago to the present; the vertical axis represents nothing in particular. The labelled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since? 50 000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

-Which of the five common ancestors, labelled V-Z, has been least successful in terms of the percentage of its derived species that are extant?

A) V
B) W
C) X
D) Y
E) Z