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 Q]: 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?
[EX A]: batteries, energy., energy, transformation

[EX Q]: Question: Electric cars use large batteries, rather than gasoline, for power. This is an example of electric energy being converted into _________. (A) heat energy (B) motion energy (C) light energy (D) chemical energy?
[EX A]: Electric, cars, electric, energy, converted

[EX Q]: Question: A student is studying the conduction of heat through different materials. He places each of three identically-sized blocks of rubber, copper, and wood on three different hot plates. On top of each block, he places a 2-gram piece of ice and then turns each hot plate on to warm. Based on the given scenario, what variable would the student measure to determine which material is the best conductor of heat? (A) Density of each material (B) Temperature of each material when the ice begins to melt (C) Time required for the ice to completely melt (D) Temperature of each hot plate?
[EX A]:
conduction, heat, materials., identically-sized, blocks, wood, hot, plates., top, piece, ice, hot, plate, variable, measure, determine, material, conductor, of