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: To safely *** an *** using ***, what should students always do?  (A) Work in large groups. (B) Wear safety goggles. (C) Wear short sleeves. (D) Keep a window open.
[EX A]: E.

[EX Q]: Question: Which of the following *** is *** for the ***?  (A) recycling waste (B) conserving water (C) producing waste (D) reducing pollutio.
[EX A]: E.

[EX Q]: Question: Which of the following is an example of a harmful relationship between living organisms?  (A) Birds live in a maple tree. (B) A butterfly carries away pollen on its legs. (C) A puppy has intestinal worms. (D) A fungus feeds on a rotting log.
[EX A]:
C.