Which is an example of a competitive relationship?

a.
barnacles living on a whale's back feeding on particles in the water

b.
fungus growing around plant roots causing them to grow better

c.
saguaro cactus and sagebrush both needing water in the desert

d.
tapeworm feeding off the nutrients within a human's intestines

where is the scientific experiment?

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms