Besides the Obvious Fact That Chemical Mutagens Are Dangerous to Handle

Besides the obvious fact that chemical mutagens are dangerous to handle, another major disadvantage to their use is that __________.

A) most of these mutations are immediately lethal
B) most chemically induced changes are detectable only by sequencing
C) chemical mutagens activate transposons
D) two or more generations of further matings are required to isolate them
E) they alter all A-T and C-G base pairing