What is a molecular clock?

Question

A)a tool scientists use to date fossils
B)a tool scientists use to determine how many mutations a species accumulates over time
C)a tool scientists use to determine how long two species have been evolving independently
D)a tool scientists use to determine how long it takes to sequence a strand of DNA

My Answer: A
I think B could be a possibility too but Im pretty sure its A.

Answer 1

I think there's a better answer.

http://en.wikipedia.org/wiki/Molecular_clock

Answer 2

I think what it is saying there implies that its C. is that right? :)

Answer 3

Yes, I think C is the best answer.
What does your book say?

Answer 4

thanks :) I don't have one....