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: Which of the following types of energy is lightning? (A) Solar (B) Heat (C) Nuclear (D) Electrical?

SOLUTION: types, energy, lightning?

PROBLEM: Question: Which conclusion is best supported by a tree-growth ring that is much narrower than the other growth rings? (A) Crops grew well that year. (B) One year was unusually dry. (C) The tree was planted long ago. (D) The area used to have more trees.?

SOLUTION: conclusion, tree-growth, ring, narrower

PROBLEM: Question: A family goes on vacation for a week. When they return home they discover that some vegetables in their refrigerator have gone bad. What is the most environmentally responsible thing for them to do with the rotten food? (A) toss it into a fire pit and burn it (B) throw it in the trash to be taken to a landfill (C) put it in a compost pile to use for plant food (D) take it back to the grocery store and try to get their money back?

SOLUTION:
vegetables, bad., environmentally, responsible, thing, rotten, food?