Instructions: 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.
Input: Pat is learning how energy flows through an ecosystem. Pat understands that animals get energy from plants. What do plants do that allow animals to get energy from them?  
 (A) Plants keep water in their roots. (B) Plants release nitrogen into the soil. (C) Plants provide shelter from the weather. (D) Plants make sugar in the presence of light.
Output:
D