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: Which two systems primarily function to rid the human body of the wastes resulting from cellular energy production?

Ex Output:
systems, function, rid, human, body, wastes


Ex Input:
Question: Base your answers on the information below. One hot, summer day it rained very heavily. After the rain, a plastic pan on a picnic table had 2 cm of rainwater in it. Four hours later, all the rainwater in the pan was gone. Which process caused the rainwater in the pan to disappear as it sat outside in the hot air? (A) condensation (B) evaporation (C) precipitation (D) erosion?

Ex Output:
2, cm, all, pan, caused


Ex Input:
Question: Water helps living things survive by (A) bringing in gases. (B) keeping them clean. (C) creating food. (D) moving materials.?

Ex Output:

Water, helps, things, survive