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 type of organism is the best at fixing nitrogen?  
 (A) bacteria (B) fungi (C) protists (D) animals

Output: A


Input: Consider Input: Which scientist is known for his genetics experiments with pea plants?  
 (A) Charles Darwin (B) Gregor Mendel (C) Carolus Linnaeus (D) Robert Hooke

Output: B


Input: Consider Input: Which model can be used to trace genetic inheritance?  
 (A) life cycle (B) pedigree chart (C) food web (D) energy pyramid


Output: B