What is the molecular clock and how is it used in evolutionary studies?

• A. A fossil morphology-based clock uses morphological changes and assumes a constant rate.
• B. A method that uses the rate of genetic mutations to estimate divergence times; assumes a relatively constant mutation rate.
• C. A method that uses current population sizes to infer historical events.
• D. A method that compares protein folding patterns to date speciation.

Answer: (B)