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: When ice cream is left out of a freezer, the ice cream changes from a (A) solid to a gas (B) gas to a liquid (C) solid to a liquid (D) liquid to a gas?
Example Output: ice, cream, left, changes

Example Input: Question: Electric cars use large batteries, rather than gasoline, for power. This is an example of electric energy being converted into _________. (A) heat energy (B) motion energy (C) light energy (D) chemical energy?
Example Output: Electric, cars, electric, energy, converted

Example Input: Question: The presence of an animal fossil in a rock gives evidence of (A) what hunting behaviors the animal used (B) how many babies the animal had (C) exactly when the animal was born (D) the time period the animal lived in?
Example Output:
presence, animal, fossil, rock, evidence