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.

Input: Consider Input: Question: Which area is coldest? (A) rainforest (B) tundra (C) grassland (D) reef?

Output: area, coldest?


Input: Consider Input: Question: Trevor takes his radio to the beach. He uses batteries to supply energy. The energy transformation occurring is ___. (A) sound to heat and chemical (B) electrical to chemical and some heat (C) chemical to heat with a small amount of sound (D) chemical to sound and some heat?

Output: batteries, energy., energy, transformation


Input: Consider Input: Question: What change of energy is exhibited when a television is turned on? (A) Potential energy changes to kinetic and heat energy. (B) Sound energy changes to electrical and heat energy. (C) Electrical energy changes to sound, light, and heat energy. (D) Mechanical energy changes to electrical and heat energy.?


Output: change, energy, television, on?