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: How long does the Earth take to complete one revolution around the sun? (A) 1 day (B) 1 week (C) 1 month (D) 1 year?

Ex Output:
Earth, one, revolution, sun?


Ex Input:
Question: Troy pours himself a glass of lemonade with ice. He leaves his glass of lemonade on the countertop for approximately ten minutes, while he answers the telephone. When Troy returns to drink his lemonade, he notices that the outer part of his glass has moisture on it. This real world example relates to what process in the water cycle? (A) Precipitation (B) Evaporation (C) Condensation (D) Photosynthesis?

Ex Output:
lemonade, ice., leaves, glass, countertop, ten, outer, part, glass, moisture, example, process, water, cycle?


Ex Input:
Question: Which of the following activities is harmful for the environment? (A) recycling waste (B) conserving water (C) producing waste (D) reducing pollution?

Ex Output:

harmful, environment?