In a Sequence of DNA Taken from Various Species of Snails

Multiple Choice

In a sequence of DNA taken from various species of snails, researchers have found that the rates of nonsynonymous substitutions and synonymous substitutions are roughly the same. What can we infer from this pattern?

A) Transversions are more common than transitions.
B) Most of the amino-acid changes are neutral.
C) Strong stabilizing selection is acting on this gene.
D) Strong selection for change is acting on this gene.
E) None of the above