Question: Which sentence uses correct subject-verb agreement?

Options:

1. The flock of birds are flying south.
2. The flock of birds is flying south.
3. The flock of birds were flying south.
4. The flock of birds fly south.

Correct Answer: The flock of birds is flying south.

Solution:

The subject \'flock\' is singular, so it takes the singular verb \'is\'.