TASK DEFINITION: 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'.
PROBLEM: Question: Which physical *** do some *** have that helps them *** in the Arctic?  (A) growing tall to hide in trees (B) changing fur color to hide from predators (C) developing large paws to protect themselves from the wind (D) producing shallow root systems to protect themselves from the cold ai.

SOLUTION: E.

PROBLEM: 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.

SOLUTION: E.

PROBLEM: Question: Water freezing *** *** *** *** ***  (A) liquid changing to a solid (B) solid changing to a liquid (C) gas changing to a solid (D) gas changing to a liquid.

SOLUTION:
A.