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: James and Jordan roll their cars across the *** living room ***. They notice that they are not moving as fast as they had when they played on the *** kitchen ***. Which *** is responsible for slowing down the cars?  (A) Wind (B) Gravity (C) Thrust (D) Frictio.

Ex Output:
D.


Ex Input:
Question: The main function of the heart is to ___.  (A) pump blood (B) remove wastes (C) produce arteries (D) collect oxyge.

Ex Output:
A.


Ex Input:
Question: *** *** *** *** energy source *** *** all weather ****** *** precipitation*** ****** *** ***?  (A) the Sun (B) the Moon (C) Earth's gravity (D) Earth's rotatio.

Ex Output:

A.