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

Ex Output:
A


Ex Input:
Vehicle exhaust contains a form of pollution called particulate matter. Technologies are being developed to reduce the amount of particulate matter in exhaust. A vehicle that produces less particulate matter would have the greatest impact on which aspect of human health?  
 (A) heart health (B) respiratory health (C) the rate of birth defects (D) weight and physical fitness

Ex Output:
B


Ex Input:
When the environment changes more quickly than a species can adapt, the species may become  
 (A) extinct (B) dominant (C) diverse (D) overpopulated

Ex Output:

A