I must not become emotional. The facts and the results of my experiments are clear, and the more sensational aspects of my own rapid climb cannot obscure the fact that the tripling of intelligence by the surgical technique developed by Drs. Strauss and Nemur must be viewed as having little or no practical applicability (at the present time) to the increase of human intelligence.

How does Charlie’s intelligence at this point in the story advance the plot?

It prompts him to ask Dr. Strauss to help him prevent his memory loss.
It helps him understand that he must eventually get his old job back.
It makes him feel sad and regretful about his decision to participate in the study.
It allows him to understand how and why he is losing many of his new abilities.