Applied the process of elimination to get at this. The answer for this one would be quite simple for those who've studied science I suppose, because all that this question is trying to do is confuse you with its wording.
Quote:
In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly, and genetic mutations occurred at random in the populations. These experiments show that all genetic mutation is random.
Which one of the following, if true, enables the conclusion to be properly drawn?
(A) Either all genetic mutations are random or none are random.
Correct answer.
The stem gives you information that the mutations occurred at random in the population. This statement is telling you that all genetic mutations either occur randomly, or none occur randomly. Putting two and two together gives us that since mutations occurred at random in the experiment, all mutations will always be random (which is the conclusion it wants us to arrive at).
(B) The bacteria tested in the experiments were of extremely common forms.
Not correct. If common forms of bacteria have mutations at random, how can we conclude that all mutations occur randomly?
(C) If all genetic mutations in bacteria are random, then all genetic mutations in every other life form are random also.
Not correct. This basically picks up the conclusion that we want to arrive at and uses it to further confuse the reader.
(D) The kind of environment in which genetic mutation takes place has no effect on the way genetic mutation occurs.
Not correct. Doesn't point us anywhere.
(E) The nutrients used were the same as those that nourish the bacteria in nature.
Not correct. Doesn't point us anywhere.