While walking along a trail in the woods you notice that your dog walks over to a tree and urinates on the base of the largest tree on the trail. Your dog's behavior is an example of?

chemical communication.

Explanation:

There are four different methods or ways through which an animal communicates including tactile, visual, chemical, and auditory. A few animals depend on more one form of communication rather than others. These methods are being used by animals to ward off threats, show affection, and/or attract towards a mate.

Chemical Communication: The term chemical communication is defined as a method through which an animal communicates with that of other animals or species. An animal often leaves scent to signify territory or attract a mate.

In the question above, the dog's behavior is an example of chemical communication.