instruction:
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.
question:
Question: Which is a process that most likely formed the Appalachian Mountains found in the eastern part of North America? (A) earthquake (B) folded rock (C) plate tectonics (D) volcanic activity?
answer:
process, formed, Appalachian, Mountains


question:
Question: Which form of energy is needed to change water from a liquid to a gas? (A) heat (B) mechanical (C) chemical (D) sound?
answer:
energy, change, water, liquid, gas?


question:
Question: A layer of solid brittle rock comprises the outer 100 kilometers of Earth. This layer, which contains both the crust and the upper mantle, is called the (A) core. (B) sediment. (C) lithosphere. (D) hemisphere.?
answer:

100, kilometers, Earth., contains, crust, upper