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.

Input: Consider Input: Question: Which pair of English and metric units has most nearly the same value? (A) liter and quart (B) gram and ounce (C) kilogram and pound (D) kilometer and mile?

Output: English, metric, units, value?


Input: Consider Input: Question: Which of these would best help a scientist discover a new planet? (A) making a model of outer space (B) asking questions to other scientists (C) collecting information about planets (D) looking at the night sky with a telescope?

Output: help, discover, new, planet?


Input: Consider Input: Question: A student provides the following directions for brushing teeth: Turn on the water. Fill the glass with water and leave the water running. Put toothpaste on the toothbrush. Brush for two minutes. Rinse mouth with the water from the glass. Rinse the toothbrush with the running water. Turn off the water. Which change in these directions would conserve the most water? (A) Brush for three minutes. (B) Turn the water off before brushing. (C) Rinse mouth with the running water. (D) Use less toothpaste on the toothbrush.?


Output: brushing, teeth:, change, directions, conserve