You will be given a definition of a task first, then some input of the task.
You are given a science question (hard-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Robert is thinking about buying a new refrigerator. His old refrigerator runs at about 43% efficiency. Which most likely accounts for the remaining 57% of the energy?
(A) It is used up by the light in the refrigerator. (B) It is released to the surroundings as heat. (C) It is converted into mechanical energy. (D) It stored as a form of potential energy.
Output:
B