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.

Which unit of measurement describes an object's length?  
 (A) meter (B) kilogram (C) liter (D) degree
A

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
A

Which inventor had the greatest impact on the development of artificial light?  
 (A) Charles Darwin (B) Albert Einstein (C) Thomas Edison (D) Benjamin Franklin

C