Detailed Instructions: 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.
See one example below:
Problem: Question: Which type of energy does a person use to pedal a bicycle? (A) light (B) sound (C) mechanical (D) electrical?
Solution: energy, pedal, bicycle
Explanation: Clearly the words "energy", "pedal" and "bicycle" are necessary and enough to understand the category of the energy associated with this process, i.e. "mechanical". Other words are not necessary to inferring the correct answer.

Problem: Question: What is the relationship between the Earth's rotations and the Sun? (A) One rotation of the Earth is equivalent to one day. The half of the Earth facing the Sun has daytime and the half facing away has nighttime. (B) One rotation of the Earth is equivalent to one month. As the Earth rotates, the Sun goes through many phases. (C) One rotation is equivalent to a day. The Sun, stars, and the Moon rise in the east and travel across the Earth in a linear fashion. (D) One rotation of the Earth is equivalent to one year. It takes that long for the Sun to go around the Earth.?
Solution:
relationship, Earth's, rotations, Sun?