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: The *** heard when a *** *** is *** is caused by  (A) vibration. (B) refraction. (C) momentum. (D) acceleration.
Example Output: A.

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.

Example Input: Question: When an octopus feels threatened, it can release black ink into the water. The ink MOST likely helps the octopus  (A) move quickly through the water. (B) breathe oxygen from the water. (C) hide from predators. (D) use food faster.
Example Output:
C.