In an Experiment, Researchers Split a Bacterial Colony in Two

In an experiment, researchers split a bacterial colony in two, allowing each of the new colonies to evolve separately.They then sequence a gene from colony 1 and colony 2.In the common ancestor, at nucleotide site 327 there is G.In colony 1, there is C; in colony 2, there is C.This is an example of a _______ substitution.

A) single
B) coincident
C) parallel
D) back
E) multiple