TASK DEFINITION: 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.
PROBLEM: Question: Steel cans are separated from aluminum cans in a recycling center. Which of the following is the best way the recycling center can separate the steel cans from the aluminum cans? (A) sort the cans by size (B) put the cans in water (C) cool the cans to a low temperature (D) put the cans under an electromagnet?

SOLUTION: recycling, center, separate, steel, aluminum

PROBLEM: Question: A student riding a bicycle observes that it moves faster on a smooth road than on a rough road. This happens because the smooth road has (A) less gravity(B) more gravity(C) less friction(D) more friction?

SOLUTION: faster, smooth, rough, smooth

PROBLEM: Question: In what way can bacteria be good for the human body? (A) Bacteria help the body have strong bones. (B) Bacteria help maintain body temperature. (C) Bacteria help deliver oxygen to the cells. (D) Bacteria help break down food.?

SOLUTION:
bacteria, good, human, body?