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:
Which two body systems are involved in inhaling oxygen and exhaling carbon dioxide?  
 (A) endocrine and skeletal (B) excretory and nervous (C) circulatory and respiratory (D) digestive and reproductive

Ex Output:
C


Ex Input:
Which material is most easily recycled at school?  
 (A) plastic wrap (B) notebook paper (C) ice cream sticks (D) rubber erasers

Ex Output:
B


Ex Input:
Metals that easily transfer electricity are called  
 (A) resistors. (B) magnets. (C) insulators. (D) conductors.

Ex Output:

D