Option 4 is the right collective noun: Pride. All the options are collective nouns of animal and bird groups. Let us look into the meaning of the given words:
Herd: a large group of animals, especially hoofed mammals, that live together.
Pack: a group of wild animals, especially wolves, living and hunting together.
Flock: a number of birds of one kind feeding, resting, or travelling together.
Pride: a group of lions or birds, such as ostriches or peacocks.