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.

[EX Q]: Which material best conducts heat and electricity?  
 (A) metal (B) plastic (C) rubber (D) wood
[EX A]: A

[EX Q]: 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
[EX A]: B

[EX Q]: Which Earth movement results in day and night?  
 (A) erosion (B) deposition (C) revolution (D) rotation
[EX A]:
D