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 body systems are most involved in the response when someone stubs his or her toe?  
 (A) nervous and muscle (B) muscle and endocrine (C) nervous and digestive (D) reproductive and circulatory

Ex Output:
A


Ex Input:
Which system of the human body provides protection to most of the major organs?  
 (A) skeletal system (B) circulatory system (C) respiratory system (D) muscular system

Ex Output:
A


Ex Input:
If a species is no longer able to reproduce, it will  
 (A) adapt to its environment (B) become immune to disease (C) become extinct (D) increase its population

Ex Output:

C