The introduction of a virus to control an invasive species is an example of
a. mechanical control
c. biological control
b. chemical control
d. all of the above

I believe the answers is b. biological control. Biological control is a control method in which a natural predator of an unwanted or overpopulated species is introduced in the ecosystem to control is population and bring back the balance in the ecosystem.

The introduction of a virus to control an invasive or unwanted species is an example of a biological control. A specific example of a biological control is the use of parasitic wasps to control aphids (insects that can carry out large damage to crops or plants).