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: When *** *** human considered *** *** reached *** adult stage?  (A) When cells no longer divide (B) When the human has begun to talk (C) When the human has begun to walk (D) When most growth has stoppe.
[EX A]: D.

[EX Q]: Question: *** *** *** *** *** explains *** stems transport water *** *** parts *** *** plant?  (A) through a chemical called chlorophyll (B) by using photosynthesis (C) through a system of tubes (D) by converting water to foo.
[EX A]: C.

[EX Q]: Question: *** *** *** *** *** *** *** *** *** harmful relationship *** 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.