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: A soccer player kicks a soccer ball across a field. Which factor has the most effect on the distance the soccer ball travels? (A) the color of the ball (B) the force of the kick (C) the length of the field (D) the temperature of the air?
[EX A]: soccer, ball, field., factor, effect, distance, ball, travels?

[EX Q]: Question: In Florida, both panthers and bobcats prey on white-tailed deer. How will their competition for food most likely be affected if white-tailed deer populations in Florida suddenly decreases? (A) Competition will increase between bobcats and panthers. (B) Competition will decrease between bobcats and panthers. (C) Competition will increase between white-tailed deer and bobcats. (D) Competition will decrease between white-tailed deer and panthers.?
[EX A]: panthers, bobcats, prey, deer., competition, food, affected, deer, populations, decreases?

[EX Q]: Question: A company plants trees on a bare hillside. Which of these is the BEST reason for planting the trees? (A) The trees provide oxygen for the soil. (B) The trees prevent soil from washing away. (C) The trees make shade for animals living there. (D) The trees cause animals to move to other places.?
[EX A]:
trees, bare, hillside., reason, planting, trees?