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 Input:
Question: Which best describes a characteristic of the jet stream? (A) It forms a boundary between a cold air mass and a warm air mass. (B) It creates the high winds around the eye of a hurricane. (C) It forces the hot air along the equator to rise to areas in North America. (D) It causes high pressure air masses to rotate clockwise.?

Ex Output:
characteristic, jet, stream?


Ex Input:
Question: Which statement describes a method of sexual reproduction that occurs in plants? (1) Stem cuttings are placed in water and grow roots. (2) Seeds are produced from the flower of the plant. (3) Underground stems from a plant grow into new plants. (4) A leaf falls to the soil, develops roots, and grows.?

Ex Output:
sexual, reproduction, plants?


Ex Input:
Question: Different species of carnivorous animals that share the same habitat in an ecosystem may (1) become decomposers (2) compete for food (3) produce their own food (4) mate with each other?

Ex Output:

carnivorous, animals, share, habitat, ecosystem