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: All known living things are made up of ___. (A) eggs (B) cells (C) cell walls (D) gelatin?
living, things, made

Question: Which force keeps the planets in their orbits around the Sun? (1) gravity (2) magnetism (3) electricity (4) friction?
force, planets, orbits

Question: Tyrone put two stones in a plastic bottle of water and shook it. After he stopped shaking the bottle, he observed that small pieces of the stones were floating in the water. What is the best prediction he can make based on this observation? If shaking the bottle causes pieces of stones to break off, (A) then using cold water will break off more pieces. (B) then using hot water will make the stones change colors. (C) then shaking for a longer amount of time will break off more pieces. (D) then shaking for a shorter amount of time will make the rocks change colors.?

stones, bottle, water, shook, stones, floating, prediction, observation?