Choose the correct one: A series of lectures were delivered., A series of lectures was delivered., A series of lecture was delivered., None of these

Choose the correct one: A series of lectures were delivered., A series of lectures was delivered., A series of lecture was delivered., None of these

Explanation

The phrase "A series of" is singular, so it takes the singular verb "was."

This structure emphasizes that the lectures were given as part of one unified series.