The word 'ponder' mean thinking about a certain thing carefully, even if it took a lot of time to do it. This word is often used in a situation when someone trying to find an answer in an unfamiliar situation. Because of this, it think the word 'question' has a similar meaning with ponder.
The words from the list all seem to fit a little with the definition of the word "ponder." Ponder means to "give serious or careful thought." One synonym for the word is question, while a related word is reflect. I think that question is going to be the fit for Ponder, out of the choices given here. The correct answer is C.
