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: Which animal is preparing for a *** *** in the environment?  (A) a bat flying at night (B) a deer drinking water (C) an owl eating a mouse (D) a squirrel storing nut.
[EX A]: D.

[EX Q]: Question: A student is given three identically sized blocks. Each block is made of a different material. What *** of the blocks should be examined to find out which block is made of ***?  (A) color (B) weight (C) texture (D) conductivit.
[EX A]: E.

[EX Q]: Question: A *** *** the *** of a bell. Which of the *** *** the *** of the *** to the student?  (A) electrical currents (B) magnetic signals (C) radio waves (D) vibrating ai.
[EX A]:
E.