Explain the difference between commensalism, parasitism, and mutualism and give examples of each

Commercialism is when one benefits while the other gets no harm nor benefit.
Example: the Remora rides attached to bigger types of fish or shark and eat the remains of meals left behind from the organism they are attached to. 

Parasitism is when benefits and the other is harmed. 
Example: A tape worm feeds off the intestines and eat what the host eats, killing the host because they are deprived of nutrients. 

Mutualism is when both benefit.
Example: when a bird is allowed to peck the food from a rhinos mouth to help the rhinos teeth and allows the birth food. 

The answer would be

C: plants and animals