I am pretty sure the answer is C. Don't take childhood for granted. He feels like he did in his childhood, but he dismissed it when younger.
A quote from the paragraph says,"<span>He supposed that, if he had ever thought about that deep-running aquifer of energy as a kid (he could not recall that he ever had), he would have simply dismissed it as a fact of life, something that would always be there, like the color of his eyes . . . ."
That is why I think the answer is C. Don't take your childhood for granted. </span>
The question that should you ask in order to understand an author's diction is that "<span>How has the author tried to prove a point with this argument?" This question will help the readers know what the author is trying to point out and what specific argument he is trying to work out.</span>
I would say read closely and highlight any important details. If the textbook belongs to the school and you're not allowed to write on it, take some notes and write down the important details on a different piece of paper.
There is no question but I would like to point out problems with that sentence. Firstly you need a full stop. Secondly make it more engaging and exciting by adding synonyms. Hope this helped