Suppose a segment of mitochondrial dna (mtdna) is compared between two similar modern-day species. it is known that this segment of mtdna changes at a steady rate of one base pair every 4 million years. compare the sequences of the two mtdna segments given below.

species a: gcactaagcatcgattt

species b: gcaccaggcactggttc

use this base principle of molecular clocks to calculate how long ago the two species diverged from a common ancestor.

a) 12 million years ago
b) 8 million years ago
c) 48 million years ago
d) 24 million years ago