1．According to scientists at the University of California, the pattern of changes that have occurred in human DNA over the millennia indicate the possibility that everyone alive today might be descended from a single female ancestor who lived in Africa sometime between 140,000 and 280,000 years ago.
(A) indicate the possibility that everyone alive today might be descended from a single female ancestor who
(B) indicate that everyone alive today might possibly be a descendant of a single female ancestor who had
(C) may indicate that everyone alive today has descended from a single female ancestor who had
(D) indicates that everyone alive today may be a descendant of a single female ancestor who
(E) indicates that everyone alive today might be a descendant from a single female ancestor who

here the phrase "that have occured" gives us the plural verb. So it should be "indicate" rather than "indicates". also in this forum i have seen a post in which it was said that in "X of Y" form, if Y is plural then the verb should also be plural...still not sure though.

anyone pls help on this one with proper explanation.

One more of the kind

2. Biologists believe that they have found one of the substances that tell individual genes both when to become active and when to remain quiescent in the earliest phases of an embryo's development.

(A) tell individual genes both when to become active and when to remain
(B) tell individual genes both at which time they should become active and should remain
(C) tells individual genes both when to become active and when to remain
(D) tells individual genes both when to activate and when to
(E) tell an individual gene both about when it should become active and when it should remain

Thanks in advance