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: *** *** *** *** *** result *** *** decrease *** *** polar bear population *** *** ***?  (A) An increase in the amount of grass (B) An increase in the fish population (C) A decrease in the fish population (D) A decrease in the human populatio.
[EX A]: C.

[EX Q]: Question: What will most likely happen to an *** *** that has been *** and *** at the bottom of a ***?  (A) It will never change. (B) It will change into a sedimentary rock. (C) It will change into a bigger igneous rock. (D) It will change into a metamorphic rock.
[EX A]: E.

[EX Q]: Question: Which of the *** *** a *** ***?  (A) a sugar cube dissolving in water. (B) ice cubes forming in a freezer. (C) ice cream melting in a bowl. (D) a cake baking in an oven.
[EX A]:
E.