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: Steel cans are separated from aluminum cans in a recycling center. Which of the following is the best way the recycling center can separate the steel cans from the aluminum cans?  (A) sort the cans by size (B) put the cans in water (C) cool the cans to a low temperature (D) put the cans under an electromagne.
[EX A]: D.

[EX Q]: Question: Plants transform energy when they make their own food. Which type of energy is used by plants for making food?  (A) electrical (B) heat (C) light (D) mechanica.
[EX A]: C.

[EX Q]: Question: Which *** help to *** *** such as bacteria that enter the human ***?  (A) red blood cells (B) liver cells (C) white blood cells (D) brain cell.
[EX A]:
C.