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.

Example Input: Question: Within a substance, atoms that collide frequently and move independently of one another are most likely in a?
Example Output: atoms, collide, frequently, move, independently

Example Input: Question: In what way can bacteria be good for the human body? (A) Bacteria help the body have strong bones. (B) Bacteria help maintain body temperature. (C) Bacteria help deliver oxygen to the cells. (D) Bacteria help break down food.?
Example Output: bacteria, good, human, body?

Example Input: Question: Which physical characteristic do some organisms have that helps them survive in the Arctic? (A) growing tall to hide in trees (B) changing fur color to hide from predators (C) developing large paws to protect themselves from the wind (D) producing shallow root systems to protect themselves from the cold air?
Example Output:
physical, characteristic, organisms, survive, Arctic?