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: Early scientists most likely saw a discharge of electricity for the first time when observing a  
 (A) waterfall (B) rainbow (C) lightning storm (D) volcano erupting
Example Output: C

Example Input: A meeting of scientists, called a symposium, occurs every year to share recent research about the atmosphere of Earth. This symposium mainly serves which purpose in science?  
 (A) to test research methods used by other scientists (B) to develop questions about space research (C) to discuss the meaning of new discoveries (D) to explain gas properties to the general public
Example Output: C

Example Input: Pond ecosystems depend on the water cycle to ensure the survival of the animals that live in or near the pond. If a drought reduces the water level, which population of animals would be most affected?  
 (A) duck (B) fish (C) mouse (D) snake
Example Output:
B