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.

Ex Input:
Jeannie put her soccer ball on the ground on the side of a hill. What force acted on the soccer ball to make it roll down the hill?  
 (A) gravity (B) electricity (C) friction (D) magnetism

Ex Output:
A


Ex Input:
Which involves the greatest variety of cell types?  
 (A) a tissue (B) an organ (C) an organ system (D) an organism

Ex Output:
D


Ex Input:
The scientific name for a giraffe is Giraffa camelopardalis. What two levels of classification does this name represent?  
 (A) family and order (B) kingdom and genus (C) phylum and domain (D) genus and species

Ex Output:

D