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: *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***.  (A) dissolving (B) deposition (C) weathering (D) erosion.
Example output: E.
Example explanation: All the words are dropped, so the correct answer should be 'E' that stands for "I don't know".
Q: Question: Which of the following statements best explains why the tilt of Earth on its axis causes summer to be warmer than winter in the Northern Hemisphere?  (A) The warm ocean currents flow from the tropics to the Northern Hemisphere in the summer. (B) The rays of the Sun strike the Northern Hemisphere more directly in the summer. (C) The greenhouse effect increases in the Northern Hemisphere in the summer. (D) The Northern Hemisphere is closer to the Sun in the summer.
A:
B.