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: Scientists use models that show the features of an atom. A scientist should use a model that  
 (A) was the first to be developed (B) was most recently developed (C) shows the arrangement most clearly (D) shows the details needed for a specific purpose
Output:
D