instruction:
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'.
question:
Question: What is the *** *** of an element that still has the *** of that element?  (A) an atom (B) a compound (C) an electron (D) a molecul.
answer:
E.


question:
Question: Which of the *** would *** in a *** in the *** *** *** in the ***?  (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.
answer:
E.


question:
Question: *** *** guitar ***is *** sound *** produced ***  (A) the size of the guitar. (B) the metal on the guitar. (C) the wood on the guitar. (D) the vibrations of the string.
answer:

D.