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 Q]: Question: Which is the best example of ***?  (A) using low energy appliances (B) washing and reusing plastic cups (C) using empty milk cartons as flower planters (D) using aluminum cans to make new product.
[EX A]: E.

[EX Q]: Question: A group of fifth grade students go to the school park on a sunny day and measure the length of their shadows at 10:00 AM, at noon, and at 2:45 PM. To measure and record the data from their observations, they use a ___.  (A) thermometer and balance (B) clock and measuring tape (C) clock and calculator (D) clock and thermomete.
[EX A]: B.

[EX Q]: Question: *** *** *** *** *** *** ***?  (A) Both make wood. (B) Both have roots. (C) Both need moonlight. (D) Both have short lives.
[EX A]:
E.