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.

Input: Consider Input: When a tree suffers from a decreased ability to transport materials within the phloem, what is directly impacted?  
 (A) volume of water in the xylem (B) flow of necessary nutrients (C) response to environmental factors (D) rate of photosynthesis in leaves

Output: B


Input: Consider Input: Which of the following is the main role of flowers found on most flowering plants?  
 (A) to take in air (B) to produce seeds (C) to absorb nutrients (D) to protect the stem

Output: B


Input: Consider Input: Which parts of an atom are reactive during a chemical process?  
 (A) electrons (B) protons (C) neutrons (D) molecules


Output: A