The correct answer is A. Mutualism
Step-by-step explanation:
The relationship between the bird and large mammals described implies benefits for the species involved because the bird can obtain food and nutrients by eating insects and the large mammals can avoid the insects' bite, which can cause diseases. This type of relationship, in which two species help each other is known as mutualism because the species are mutually dependent and both benefit. This does not occur in other relationships such as parasitism or commensalism because in this only one species benefits.