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.

Example Input: Question: A flower produces seeds that fall to the ground and grow into new plants that produce more flowers. The seeds begin to grow by the process of (A) fertilization. (B) germination. (C) maturation. (D) pollination.?
Example Output: flower, seeds, grow, process

Example Input: Question: Why is water considered to be a renewable resource? (A) Water can be used over again. (B) Water can be found all over Earth. (C) Water can dissolve other substances. (D) Water is needed by organisms to stay alive.?
Example Output: water, renewable, resource?

Example Input: Question: A student forgot to take his glasses off in the shower. What is the most likely reason his glasses are foggy? (A) condensation (B) evaporation (C) melting (D) saltwater intrusion?
Example Output:
shower., reason, glasses, foggy?