Answer:
Nuclear fusion.
Explanation:
In nuclear fusion, two or more small nuclei combine to form a single, larger nucleus.
Answer:
the correct answer is the second option
The alveoli are surrounded by tiny blood vessels, called capillaries carrying blood to and from the heart.
Homeostasis: A state of balance reached through reactions within a cell or organism.
Metabolism: The total of all chemical reactions within an organism.
Organism: Any living thing that takes in food, grows, and reproduces.