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: Scientists have studied the specific stages in the life cycle of stars. In which stage do stars spend most of their lifetime?  
 (A) red giant (B) black dwarf (C) white dwarf (D) main sequence
Example Output: D

Example Input: Why do the Sun and Moon appear to move across the sky?  
 (A) The rotation of the solar system makes the Sun and Moon seem to move. (B) The rotation of Earth makes the Sun and Moon seem to move. (C) The Sun and Moon revolve around Earth. (D) Earth revolves around the Sun and the Moon.
Example Output:
B