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:
In an accurate diagram of the solar system, which object would be shown closest to Earth?  
 (A) the Moon (B) the asteroid belt (C) Mars (D) Saturn

Ex Output:
A


Ex Input:
A leaf is covered in mud during a landslide. After one million years, this leaf will most likely be ___.  
 (A) a fossil (B) an animal species (C) a new plant species (D) a nonrenewable fuel

Ex Output:
A


Ex Input:
In humans, digestion begins in the mouth. The complete process of digestion occurs with the help of many different parts of the body. Which term best identifies the parts of the body that carry out the function of digestion?  
 (A) an organ (B) an organism (C) a system (D) a tissue

Ex Output:

C