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.

Example Input: Some events on Earth happen instantly while others take thousands of years to occur. Which process takes the longest time to complete?  
 (A) rivers rising due to storms and floods (B) evaporation of water from the leaves of a plant (C) weathering of a rock to form small rocks and sand (D) movement of small pieces of rock by flowing water
Example Output: C

Example Input: A meteoroid becomes a meteorite when it  
 (A) impacts the surface of a planet. (B) encounters the atmosphere of a planet. (C) makes a complete orbit around a planet. (D) starts to burn up in the atmosphere of a planet.
Example Output: A

Example Input: What gas in the air do we need to breathe in order to live?  
 (A) nitrogen (B) oxygen (C) carbon dioxide (D) hydrogen (E) water vapor
Example Output:
B