You are given an elementary science question along with a few answer options. List all the words from the question that are essential and sufficient for choosing the correct answer option. Keep in mind that essential words are necessary to understand the meaning of the given question. However, non-essential words provide little information needed to select the correct answer. You can think about it like this: If the question was in another language, knowing the meaning of which words were necessary and enough for you to understand the question and answer it?. If your answer consists of multiple spans of words from the question, separate those using a comma (", "). Do not generate any word that is not present in the question. Make sure that your response is contained in the given question and the words are in the same order as the question.
 Grammatical correctness is not important.

Ex Input:
Question: Jerome is running in a race. Which body system will deliver more oxygen to his muscle cells? (A) Nervous (B) Skeletal (C) Muscular (D) Circulatory?

Ex Output:
body, system, deliver, oxygen, muscle, cells?


Ex Input:
Question: Which object is the best conductor of electricity? (A) a wax crayon (B) a plastic spoon (C) a rubber eraser (D) an iron nail?

Ex Output:
best, conductor, electricity?


Ex Input:
Question: Spiders have eight legs and usually eight eyes. Why would these traits help a spider survive? (A) These traits help it respond rapidly to what is happening around it. (B) These traits help it to spin webs and entrap its food. (C) These traits help it to scare away dangerous prey. (D) These traits help it attract a mate.?

Ex Output:

Spiders, eight, legs, eight, eyes., traits, help, survive?