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:
Kim lost her hammer outside. When she found it a few months later, some parts of the metal were covered with flaky, brown rust. Which type of change occurred when rust formed on the hammer?  
 (A) chemical (B) electrical (C) thermal (D) physical

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:
Discarded electronic devices, such as outdated computers and cell phones, contain materials that can be toxic to the environment. Which statement best explains why humans continue to use these technologies?  
 (A) Electronics have become less expensive over time. (B) Some areas have recycling programs for electronics. (C) Industries that produce electronics help the economy. (D) Humans value the benefits of these devices over their cost.

Ex Output:

D