instruction:
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.
question:
Question: Which of the following statements best explains why magnets usually stick to a refrigerator door? (A) The refrigerator door is smooth. (B) The refrigerator door contains iron. (C) The refrigerator door is a good conductor. (D) The refrigerator door has electric wires in it.?
answer:
magnets, stick, refrigerator


question:
Question: What is the approximate length of time it takes the Moon to complete one lunar cycle? (A) 14 days (B) 29 days (C) 180 days (D) 365 days?
answer:
length, time, complete, one, lunar, cycle?


question:
Question: Erin placed her shamrock plant in a dark corner. Soon she saw that the leaves had tilted toward her window. What did the plant need most from the window? (A) sunlight during the day (B) air during the day (C) darkness at night (D) warmth at night?
answer:

plant, dark, corner., leaves, tilted, toward, window., plant, need, window?