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 student notices a paw print while walking in a park. The paw print could be considered a fossil if the print was in ___.  
 (A) rock (B) topsoil (C) thick mud (D) loose sand

Ex Output:
A


Ex Input:
The greatest amount of diversity can be found among which type of organism?  
 (A) plants (B) animals (C) bacteria (D) fungi

Ex Output:
C


Ex Input:
The human body is composed of different systems made of specialized cells, tissues, and organs. Each of these structures has a specific function that aids in the survival of the human species. What is the primary function of the excretory system?  
 (A) to digest food (B) to help in defense (C) to eliminate waste (D) to enable movement

Ex Output:

C