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: As the molecules of water begin to slow down they go into a phase where they are no longer able to easily move past each other. The water is passing through a phase change and will?

Ex Output:
molecules, water, slow, phase, move, past, phase, change


Ex Input:
Question: A metric ruler can be used to measure the ____ (A) volume of a liquid. (B) circumference of a circle. (C) length of a stick. (D) curve of an oval.?

Ex Output:
metric, ruler, measure


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