Assume that a base-pair substitution mutation converts a DNA triplet (AAT) to another DNA triplet (AAA). A second mutation now changes the AAA triplet to the GAA triplet. (UUA and CUU code for leucine and UUU codes for phenylalanine.) This second mutation is an example of a(n):
A. transversion.
B. intragenic suppressor.
C. loss-of-function mutation.
D. intergenic suppressor.
E. frameshift