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: Two identical books are on opposite ends of a table. Which of these would increase the gravitational force exerted between the two books?  
 (A) decrease the distance between the books (B) decrease the mass of the books (C) decrease the mass of the table (D) decrease the temperature in the room
Example Output: A

Example Input: A model of the Moon would be different from a model of Earth in that the Moon should  
 (A) be smaller than Earth. (B) have a source of light inside. (C) have a smoother surface than Earth. (D) have fewer impact craters on the surface.
Example Output: A

Example Input: A lab technician places a colony of bacterial cells in a nutrient-rich growth medium. Which event is the technician most likely to observe with a microscope?  
 (A) cell division (B) cellular respiration (C) heat production (D) food storage
Example Output:
A