In this task, you need to answer basic science questions. For each question, several terms are intentionally masked with ***. This masking can cover very few or many of the question words. Clearly, if masked terms are important, the modified question will be impossible to answer. Please indicate the correct answer with one of the following responses: "A", "B", "C", "D" or "E". While "A"-"D" correspond to the answer options provided in the input, "E" represents "I don't know" for questions that do not provide enough information. Respond via "E" if the question is not answerable. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'.

[EX Q]: Question: *** *** *** difference *** *** food chain *** *** food web?  (A) A food chain always ends with a primary consumer. (B) A food web is made up of many food chains. (C) A food web only shows one flow of energy through the ecosystem. (D) A food chain is made up of many food webs.
[EX A]: B.

[EX Q]: Question: Martin is writing a report for science class about how the tilt of Earth *** living organisms. Which subject should Martin include in his report that is directly *** by Earth's tilt?  (A) night and day (B) cloud formation (C) phases of the Moon (D) changing of the season.
[EX A]: D.

[EX Q]: Question: When an ice cube melts, its state of matter changes from a  (A) gas to a liquid (B) solid to a liquid (C) liquid to a solid (D) solid to a gas.
[EX A]:
B.