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.

Q: Question: Materials put into a compost pile include grass clippings, kitchen scraps, and some paper. Who or what recycles these materials in a compost pile? (A) soil (B) bacteria (C) a landfill (D) leaves?

A: recycles, materials, compost, pile?
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Q: 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.?

A: bacteria, good, human, body?
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Q: Question: Toads lay their eggs in ponds. Tadpoles hatch from the eggs and eat the plants floating in the pond. Which resource is most important for toads to survive? (A) grass (B) rocks (C) trees (D) water?

A:
Toads, eggs, ponds., Tadpoles, hatch, eat, plants, floating, resource, important, survive?
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