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'.

Ex Input:
Question: Which of the following is the BEST example of something that causes a *** *** in the earth's surface?  (A) rainbows (B) floods (C) global warming (D) glacier.

Ex Output:
E.


Ex Input:
Question: *** is learning about *** ***s of ***. Which is an *** of a *** ***?  (A) webbed feet on a duck (B) migration of songbirds (C) sharp eyesight of an eagle (D) camouflaged colors on a fro.

Ex Output:
E.


Ex Input:
Question: Changes in weather are caused by ___.  (A) movement of air (B) the Earth's tilt on its axis (C) the Sun's orbit (D) consistent temperature.

Ex Output:

A.