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 two body systems are involved in inhaling oxygen and exhaling carbon dioxide?  
 (A) endocrine and skeletal (B) excretory and nervous (C) circulatory and respiratory (D) digestive and reproductive
C

How do traits of animals such as ear shape, nose shape, and hair color most often get passed to offspring?  
 (A) sexual reproduction (B) asexual reproduction (C) adaptation (D) instinct
A

In a zoo located in a warm region, which should be included in the polar bear exhibit?  
 (A) food bowl with fruit (B) hot, bright lights (C) cold-water pool (D) tall palm trees

C