I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
Biotic would mean living so fish and sea plants
Answer:
D. Oxygen
Explanation:
Plants absorb carbon dioxide (CO2) and release oxygen for humans and animals to breathe in. Afterward, they'll release CO2 for plants to absorb, which forms a cycle.
