You are given a science question (hard-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: A tropical rain forest contains many tall trees. Smaller plants with large leaves grow at the base of the tall trees. The large leaves are most likely an adaptation of the plant due to which condition?  
 (A) lack of sunlight (B) lack of oxygen (C) lack of water (D) lack of food
Example Output: A

Example Input: Which mixture contains ingredients that can be easily separated?  
 (A) bread (B) fruit salad (C) ocean water (D) soda water
Example Output: B

Example Input: If you throw each one of these things away, which will decay fastest?  
 (A) A glass bottle (B) A metal can (C) A plastic bottle (D) An apple core
Example Output:
D