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: Spring tides occur during which lunar phases?  
 (A) first quarter and last quarter (B) full moon and new moon (C) when the moon is waxing (D) when the moon is waning
Example Output: B

Example Input: Which of these shows the correct order for the central dogma of molecular biology?  
 (A) DNA to protein to RNA (B) RNA to DNA to protein (C) protein to DNA to RNA (D) DNA to RNA to protein
Example Output: D

Example Input: Which body system functions by bringing in oxygen and removing carbon dioxide?  
 (A) endocrine (B) respiratory (C) digestive (D) urinary
Example Output:
B