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 Q]: Which difference between water and ice results in ice floating on cold water?  
 (A) heat (B) shape (C) density (D) volume
[EX A]: C

[EX Q]: Which is the greatest benefit of sexual reproduction?  
 (A) capable of reproducing by meiosis (B) ability to reproduce without a mate (C) ability to produce genetically different offspring (D) capable of producing offspring genetically identical to parent
[EX A]: C

[EX Q]: Why do planets stay in orbit around the Sun?  
 (A) attraction of gravity (B) effect of inertia (C) frictional force (D) rotational force
[EX A]:
A