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: The human immunodeficiency virus (HIV) causes AIDS. The first known human cases AIDS were in Africa in the late 1950s. Since then, tens of millions of people have died from the disease, and tens of millions more people all over the world are infected. Which term best describes the disease AIDS?  
 (A) isolated cases (B) outbreak (C) epidemic (D) pandemic

Output: D


Input: Consider Input: Why does the leaf of a plant look green?  
 (A) Because it absorbs green light (B) Because it reflects green light (C) Because it absorbs only yellow and blue light (D) Because it reflects a mixture of yellow and blue light

Output: B


Input: Consider Input: Which model best illustrates the wave property that enables scientists to explore Earth's interior using seismic waves?  
 (A) shining a light on rock in a bowl (B) shining a light through a prism (C) shining a light through a periscope (D) shining a light on a sundial


Output: B