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: *** *** *** *** *** result *** *** decrease *** *** polar bear population *** *** ***?  (A) An increase in the amount of grass (B) An increase in the fish population (C) A decrease in the fish population (D) A decrease in the human populatio.
Example Output: C.

Example Input: Question: Which of the following *** *** be *** into *** ***?  (A) nitrogen (B) zinc (C) air (D) aluminu.
Example Output: E.

Example Input: Question: Amanda found a wooden box in her grandfather's garage. The top was nailed shut. What type of simple machine should Amanda use to open the box?  (A) lever (B) pulley (C) wheel and axle (D) inclined plan.
Example Output:
A.