Correct option is C
examples of protocooperation are, the crocodile Bird (a plover) enters the mouth of the crocodile to feed on the parasitic leeches, the bird gets food and the Crocodile get rid of the blood-sucking parasites, another example is sea anemone attached to the body of hermit crab protects it from the Enemies with its nematocyst in turn the sea anemone receive pieces of food dropped by the crab and is carried to new places by it.