I believe the answer is A
Dominant m8 hope this hleps
A dog breathes in oxygen and then releases carbon dioxide when he exhales. Conversely, a tree gives off oxygen and takes in carbon dioxide. So the breath of the dog sustains the tree while the output of oxygen for the tree sustains the dog.
The answer to this would be D: physical components of the environment, such as rocks and sand. The word "biotic" mean all the living organisms within an ecosystem such as plants and animals.
