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: The basic life functions of an organism are carried on by  
 (A) cells (B) nutrients (C) atoms (D) hormones
Example Output: A

Example Input: Water at 20°C in an uncovered pan is evaporating very slowly. What could be done to the water to make it evaporate more quickly?  
 (A) Cover it. (B) Heat it. (C) Place it in the dark. (D) Put salt in it.
Example Output: B

Example Input: How can plants most likely improve air quality?  
 (A) by absorbing nutrients (B) by producing oxygen (C) by producing sugar (D) by absorbing water
Example Output:
B