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:
One important use of coal is to produce energy for homes. Coal can be burned and converted to  
 (A) wind energy. (B) nuclear energy. (C) electrical energy. (D) solar energy.

Ex Output:
C


Ex Input:
Use of nuclear fuel would most likely reduce human contributions to which environmental problem?  
 (A) ozone thinning (B) landfill creation (C) shoreline erosion (D) greenhouse heating

Ex Output:
D


Ex Input:
Which structure best protects a cactus from being eaten by animals?  
 (A) waxy coating on the stem (B) green pigment in the cells (C) sharp spines as the leaves (D) long roots near the surface

Ex Output:

C