You compare homologous nucleotide sequences among several pairs of species with known divergence times. A pair of species that diverged 1 million years ago has two nucleotide differences, a pair that diverged 2 million years ago has four nucleotide
differences, and a pair that diverged 3 million years ago has six nucleotide differences. You have sequence data for another pair of species for which the divergence time is unknown. There are five nucleotide differences between them. Based on your clock, when did their line of ancestry diverge?
A) 3.5 million years ago
B) 3 million years ago
C) 2.5 million years ago
D) 2 million years ago
Answer: C
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