THE CORRECT ANSWER IS B. THE QUESTION ASKS US TO INFER FROM THE PA...

27. The correct answer is B.

The question asks us to infer from the passage the reason that the

replica plating method is effective. The plating method involved

pressing an agar culture on velvet and then transferring that culture

to a new agar plate. The resulting pattern of mutant bacteria

matched the pattern on the original culture. The author concludes

that this indicates that the mutations were already present in the

original culture. We can deduce from this that no new mutant

bacteria developed after the transfer. Otherwise, the plating

technique would not be conclusive. This is consistent with Choice B.