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 Input:
Question: Clouds bring rain and snow to Earth's surface. How do rain and snow most support *** on Earth?  (A) They cool the land surface. (B) They carry acids into the soil. (C) They bring freshwater to land organisms. (D) They build up mountains.

Ex Output:
C.


Ex Input:
Question: Which of these human activities in a forest has a *** effect on the ecosystem?  (A) Clearing the land to build new homes (B) Planting new trees where old ones were cut down (C) Building a new highway through the area (D) Cutting down trees to make farmlan.

Ex Output:
E.


Ex Input:
Question: A student poured water into a plastic tray. The student then put the tray into the freezer. What *** 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.

Ex Output:

C.