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 student shines a flashlight on different colors of paper. Which color of paper will absorb the most light?  
 (A) Red (B) Black (C) White (D) Yellow

Ex Output:
B


Ex Input:
Sandbars form in many rivers because of  
 (A) erosion of cliffs. (B) water flowing into a lake. (C) dams being built by beavers. (D) sediment being moved downstream by water.

Ex Output:
D


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