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.

Ex Input:
A human CANNOT survive the loss of which of the following?  
 (A) The appendix (B) The liver (C) A lung (D) A kidney

Ex Output:
B


Ex Input:
Which traits would a species of nocturnal predators most likely develop over time to survive in the wild?  
 (A) a small size (B) flat, grinding teeth (C) sharp vision and hearing (D) resistance to weather changes

Ex Output:
C


Ex Input:
A student observes that a plant grows at different rates at different times. The student states that these changes must result from changes in the amount of light received by the plant. Which description of the student's statement is most accurate?  
 (A) It is an opinion and not a fact. (B) It is correct because it is based on observation. (C) It is one of several possible explanations for the evidence. (D) It is invalid because it is not based on a scientific method.

Ex Output:

C