Sixty-five million years ago, according to some scientists, an asteroid bigger than Mount Everest slammed into North America, which, causing plant and animal extinctions, marks the end of the geologic era known as the Cretaceous Period.

(A) which, causing plant and animal extinctions, marks

(B) which caused the plant and animal extinctions and marks

(C) and causing plant and animal extinctions that mark

(D) an event that caused plant and animal extinctions, which marks

(E) an event that caused the plant and animal extinctions that mark

OA is E.

D could have correct if “an event that caused plant and animal extinctions, which marks“if (see bold italics) “marks” would have been “mark” right? Since “extinctions” is the noun that is at par with the which touch rule, so which is modifying “extinctions” and not “an event” correct? Are there any exceptions to this rule?

E has the last word as “mark” since it is the “extensions” that the “that” is modifying hence the plural verb. “an event” is not the one that determines the action verb “marks”

Please confirm.