Answer:
The correct answer will be- flock defense
Explanation:
A flock is a group of same species of animals usually observed in the birds during migration.
The flock increases their fitness of survival by avoiding predators in which the one individual of the group gives a call in response to the predator.
The same predator call is repeated by every member of the flock which threatens the predator and the predator goes away. This flock response is considered as the defense response to predator and thus the mechanism is known as flock defense.
Thus, flock defense is the correct answer.