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.

Example Input: A scanning electron microscope is best suited for observing  
 (A) diffraction of light. (B) tectonic features on planets. (C) the surfaces of small objects. (D) topographical features on the ocean floor.
Example Output: C

Example Input: Which statement best describes the development of a human embryo?  
 (A) A single cell becomes many cells. (B) Each cell has a different function. (C) Many cells combine to form one cell. (D) All the cells have the same function.
Example Output: A

Example Input: Which energy source is considered nonrenewable?  
 (A) oil (B) moving water (C) sunlight (D) biomass
Example Output:
A