Question

What is often a problem when calibrating a molecular clock?

A. There are frequently not enough negative mutations to accurately calibrate the clocks.
B. There are many different clocks, each of which "ticks" at a different rate.
C. The clocks use mutations that are difficult to identify and track.
D. The frequency of crossing over is used to calibrate the clocks.​

Answer 1

C. The clocks use mutations that are difficult to identify and track.

Step-by-step explanation: