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:
Overuse of soil for farming causes local disruptions of several Earth subsystems. Which of these is a part of the biogeochemical cycle that experiences the most severe local disruption?  
 (A) release of carbon into the atmosphere (B) release of oxygen into the atmosphere (C) cycling phosphorus into the soil (D) cycling hydrogen into the soil

Ex Output:
C


Ex Input:
When oxygen combines with hydrogen, which substance is formed?  
 (A) water (B) vinegar (C) hydrochloric acid (D) hydrogen dioxide

Ex Output:
A


Ex Input:
While conducting an investigation on refraction, a teacher uses a red laser pointer to show how a beam of light is affected as it passes through several glass objects. The teacher should make sure that the  
 (A) room is totally dark. (B) light source is ultraviolet. (C) beam of light does not travel toward the students. (D) room walls are shielded with insulating material.

Ex Output:

C