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: A tropical rain forest contains many tall trees. Smaller plants with large leaves grow at the base of the tall trees. The large leaves are most likely an adaptation of the plant due to which condition? (A) lack of sunlight (B) lack of oxygen (C) lack of water (D) lack of food?

Ex Output:
Smaller, plants, large, leaves, base, tall, trees., large, leaves, adaptation


Ex Input:
Question: Which force keeps the planets in their orbits around the Sun? (1) gravity (2) magnetism (3) electricity (4) friction?

Ex Output:
force, planets, orbits


Ex Input:
Question: When the switch in a simple series circuit is closed, what happens to the light bulb that the electricity is flowing to? (A) the light cracks (B) the light goes off (C) the light burns out (D) the light comes on?

Ex Output:

series, circuit, light, bulb