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: The Grand Canyon is an example of (A) erosion. (B) deposition. (C) an earthquake. (D) volcanic activity.?
Example Output: Grand, Canyon, example

Example Input: Question: Which two processes in the water cycle are primarily responsible for the creation of a lake?
Example Output: processes, water, cycle, creation, lake?

Example Input: Question: The main source of food for a coyote population in one area is mice. Which is most likely to happen to these coyotes if a new predator begins eating the mice? (A) There will be fewer coyotes. (B) The coyotes will produce more young. (C) More coyotes will arrive from other locations. (D) Each coyote will spend less time hunting food.?
Example Output:
source, food, coyote, mice., happen, new, predator, eating, mice?