Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
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
Reason: 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.

Now, solve this instance: Question: Delilah put a container of water in the freezer and left it there overnight. The next morning she saw that the water in the container had changed to ice. Which of the following statements best explains why the water changed to ice? (A) The water gained energy. (B) The water absorbed light. (C) Mass was released from the water. (D) Heat was taken away from the water.?
Student:
water, freezer, overnight., explains, water, changed, ice?