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 *** *** to *** *** such as *** that *** the *** ***?  (A) red blood cells (B) liver cells (C) white blood cells (D) brain cell.

SOLUTION: E.

PROBLEM: Question: An ice cube is placed in a pan. The pan is placed over an open flame. Which change will most likely happen over time?  (A) The ice changes to a liquid and back to a solid. (B) The ice changes to a liquid then to a gas. (C) The ice changes to a gas and back to a solid. (D) The ice changes to a gas then to a liquid.

SOLUTION: B.

PROBLEM: Question: Which of the following is the main *** of *** *** on most *** ***?  (A) to take in air (B) to produce seeds (C) to absorb nutrients (D) to protect the ste.

SOLUTION:
E.