GWD14-38

38. GWD17-Q38:

All Y chromosomes in existence today are descended from a single ancestor’s who is thought to have lived about 140,000 years ago.

A.      a single ancestor’s who is thought to have lived

B.       a single ancestor’s who was thought to live

C.      a single ancestor whom it is thought had lived

D.      the Y chromosome of a single ancestor who is thought to have lived

E.       the Y chromosome of a single ancestor whom it was thought had lived

正确答案D,  我选B