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: Based on analysis of deep ice cores from the Arctic, scientists theorize that early humans caused air pollution. These scientists can make sure their data is correct by  (A) analyzing only melted ice cores. (B) analyzing more than one ice core. (C) comparing their data to the expected results. (D) comparing their data to modern pollution levels.
Example Output: B.

Example Input: Question: Valerie *** her *** *** *** and *** her friend. At which *** is the *** of *** *** ***?  (A) As the water almost reaches her friend (B) When the squirt gun is being pumped (C) Just before she squirts her friend (D) As the water first leaves the squirt gu.
Example Output: E.

Example Input: Question: Tobias *** his *** on a road for a *** *** ***. On average, he *** a *** *** *** *** *** *** during this ***. Which of the following was his *** *** for this *** *** ***?  (A) 10 km/hr (B) 15 km/hr (C) 20 km/hr (D) 25 km/h.
Example Output:
E.