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.

Q: Which organ is the site of gas exchange between the body and the environment?  
 (A) spleen (B) liver (C) lungs (D) pancreas

A: C
****
Q: Where do good bacteria grow to help keep people healthy?  
 (A) in the brain (B) in the blood (C) on the skin (D) on the bones

A: C
****
Q: Which statement describes a characteristic of both sexual and asexual reproduction?  
 (A) The processes require egg cells. (B) New cells are produced. (C) Two parents are required. (D) The processes produce genetically unique offspring.

A:
B
****