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 of the following statements about consumers is true? (A) They are adapted to use sunlight for photosynthesis. (B) They are organisms that make their own food. (C) They are dependent on producers for energy. (D) They are the only source of energy in an ecosystem.?

Ex Output:
statements, consumers


Ex Input:
Question: Antonio took several different measurements of an object. After he was finished, he realized that he forgot to label his measurements. Which of the following measurements could be the volume of the object? (A) 28 mL (B) 31 cm (C) 4 lbs. (D) 78 °F?

Ex Output:
measurements, volume


Ex Input:
Question: Why is competition important? (A) It makes weak organisms weaker. (B) It maintains a natural balance. (C) It eliminates predators in an ecosystem. (D) It makes populations grow larger.?

Ex Output:

competition, important?