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: Michael Faraday showed how electric current in a wire produces (A) molecules (B) chemicals (C) a vibration (D) a magnetic field?
Example Output: electric, current, wire, produces

Example Input: Question: An old T-shirt can be ripped into smaller pieces and used as rags. An empty milk jug can be used to water houseplants. Both of these are examples of how ___. (A) saving water conserves future resources (B) using old materials can waste money (C) plants need water to be healthy (D) everyday materials can be reused?
Example Output: T-shirt, ripped, rags., milk, jug, water, houseplants., examples

Example Input: Question: On Earth, water can be a solid, a liquid, or a gas. Which energy source has the greatest influence on the state of matter of water? (A) the sun (B) the wind (C) ocean currents (D) the metal core?
Example Output:
energy, source, greatest, influence, state, matter, water?