A. Multiple organ systems working together
Explanation:
All of the organ systems work together to maintain homeostasis in humans because each system does something different. For example, the circulatory system delivers oxygen rich blood to the bones and the bones create new blood cells. When one thing is wrong with one system, it affects all of the systems, like a disease. Another example of this would be the central nervous systems and endocrine working together to coordinate messages to the brain about the body's state while resting and exercising to maintain homeostasis.
Answer: possibly A
Explanation: B an C are not it because they are more like mutations. D humans don’t always become immune.
Carbon dioxide because people in other animals exhale carbon dioxide as a waste product. People and other animals need oxygen for plants produce oxygen during an important process called photosynthesis which turns the sun energy into nutrients so carbon dioxide would be the answer.
