The author doesn’t distinguish between adaptive (helpful) mutations and unhelpful mutations in P2. The author uses “typo” as part of a description of how mutations occur. But she doesn’t go into the difference between adaptive mutations an unhelpful mutations, so (A) can’t be the purpose of “typo.”

The author uses “typo” as part of a description of how mutations occur. This is part of the context for understanding how Steele’s hypothesis works. There’s no indication the author believes the mutations described in connection with “typo” are inconsequential (unimportant).

This best captures the purpose of “typo.” In the same way that one might make a small mistake when typing something out on a computer, there can be a small mistake when DNA is copied into RNA. This small mistake is a mutation.

The author doesn’t discuss or mention the potential difficulty of noticing mutations. So it wouldn’t make sense for the use of “typo” to indicate that something is easily overlooked. The issue of overlooking a mutation that has occurred isn’t relevant to P2.

The author uses the word “typo” to help us understand how a mutation might occur when transcribing from DNA to RNA. This word does involve the context of text and writing, but this doesn’t imply that the author wants to analogize the broad concept of scientific investigation to textual analysis. We’re simply discussing mutations and how they occur.