Correct Answer: flock

Solution : The correct choice is the first option.

Flock : A group of birds, typically of the same species, that fly, move, or feed together.

The meanings of the other options are as follows:

• Litter : A group of young animals born to the same mother at the same time, such as a litter of puppies or kittens.
• Pack : A group of wild animals, often predators, that hunt or travel together as a social unit, like a pack of wolves.
• Streak : A rapid and continuous movement of a group of animals, such as a streak of tigers, running closely together in a line.