The bird called the cattle egret follows large animals, such as rhinoceroses, elephants, cows, or antelope. The bird stays near them as they graze in the grasses, and eats the insects in the grass which get disturbed by the larger animals. Below is a picture of two cattle egrets near a pair of antelope.
Which of these animals gets something useful from the other in this relationship?
A.
The egret gets something useful from the antelope only.
B.
Neither animal gets anything useful from the other.
C.
The antelope gets something useful from the egret only.
D.
They each get something useful from the other.