You are given a science question (easy-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 dish of sugar water was left on a window sill. One week later, there were only sugar crystals left in the dish. The water was gone. The best explanation for the appearance of sugar crystals is  
 (A) some of the water was absorbed by the dish. (B) the air condensed. (C) the light shining on the window sill produced more sugar. (D) the water evaporated.

Ex Output:
D


Ex Input:
In one area, a large source of prey for eagles is rabbits. If the number of rabbits suddenly decreases, what effect will it most likely have on the eagles?  
 (A) Their numbers will increase. (B) Their numbers will decrease. (C) They will adapt new behaviors. (D) They will migrate to new locations.

Ex Output:
B


Ex Input:
While studying the relationship between number of trees and amount of atmospheric oxygen, which of the following would be most important to take into account?  
 (A) contributions to atmospheric oxygen from sources other than trees (B) the ways in which industrialized nations use trees (C) the root area of trees (D) the bark mass of trees

Ex Output:

A