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'.

Example Input: Question: A student wants to find out how many *** *** of *** are *** in a ***. In addition to a *** *** ***, the student should ***  (A) binoculars (B) goggles (C) a microscope (D) a hand len.
Example Output: E.

Example Input: Question: Which of the following is *** of ***?  (A) gravity (B) light (C) heat (D) ai.
Example Output: E.

Example Input: Question: A marble is dropped in a glass of water. Which *** *** the marble to the *** of the glass?  (A) electricity (B) friction (C) gravity (D) magnetism.
Example Output:
C.