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 unit of measurement can be used to describe the length of a desk? (A) centimeters (B) grams (C) liters (D) degrees Celsius?

Ex Output:
measurement, length, desk?


Ex Input:
Question: A student plans to design a new toothpaste tube that will give the same amount of toothpaste every time it is squeezed. Which should the student do first when designing the new tube? (A) make a data table of amounts of toothpaste (B) gather building materials (C) create models of old toothpaste tubes (D) draw a few possible solutions?

Ex Output:
toothpaste, tube, toothpaste, time, student, first, designing


Ex Input:
Question: When the oven door is opened halfway through baking a cake, what is most likely to decrease? (A) the cooking time (B) the cake's size (C) the amount of calories (D) the temperature in the oven?

Ex Output:

oven, door, opened, baking, decrease?