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: Which material is the best natural resource to use for making water-resistant shoes?  (A) cotton (B) leather (C) plastic (D) woo.
Example Output: B.

Example Input: Question: *** *** *** done *** *** results *** *** experiment *** not support *** hypothesis?  (A) repeat the experiment and check for errors (B) change the observations to match the hypothesis (C) redo the experiment until the expected results are obtained (D) record and analyze the data after changing the hypothesi.
Example Output: A.

Example Input: Question: Which of the following enables an animal to get oxygen?  (A) Digestive System (B) Cirulatory System (C) Respiratory System (D) Nervous Syste.
Example Output:
C.