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 of the following traits would be classified as a learned behavior of a dog?  (A) Shedding hair in the Spring (B) Ears perking up when someone approaches the front door (C) Falling asleep when tired (D) Bringing back a thrown Frisbe.
Example Output: D.

Example Input: Question: *** form *** energy *** needed *** change water *** *** liquid *** *** gas?  (A) heat (B) mechanical (C) chemical (D) sound.
Example Output: A.

Example Input: Question: What *** of the *** is the most important for the process of ***?  (A) Stigma (B) Stamen (C) Leaves (D) Ste.
Example Output:
E.