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.

Input: Consider Input: Which object is best used to demonstrate the bending of light as it passes through a substance?  
 (A) convex lens (B) flat mirror (C) opaque rod (D) concave mirror

Output: A


Input: Consider Input: Which human organ system eliminates liquid and gaseous wastes from the body?  
 (A) circulatory (B) endocrine (C) excretory (D) reproductive

Output: C


Input: Consider Input: A scientist is trying to decide whether an organism is unicellular or multicellular. Which information would help the scientist most to make her decision?  
 (A) size of the cells of the organism (B) what the organism eats (C) how many types of cells are in the organism (D) how fast the organism grows


Output: C