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.
Q: When making observations in nature, what is the best way for students to show respect for the environment?  
 (A) Stay on the paths. (B) Not take samples. (C) Take photographs. (D) Leave the area exactly as they found it.
A: 
D