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'.

[Q]: Question: What is the *** *** of an element that still has the *** of that element?  (A) an atom (B) a compound (C) an electron (D) a molecul.
[A]: E.


[Q]: Question: A student poured water into a plastic tray. The student then put the tray into the freezer. What property of the water changed as the water froze?  (A) The water became a gas. (B) The mass of water increased. (C) The water took a definite shape. (D) The flavor of the water changed.
[A]: C.


[Q]: Question: Which *** of the *** *** in *** and ***?  (A) roots (B) stem (C) leaves (D) flowe.
[A]:
E.