Which of the following statements correctly defines the boiling point of a liquid? The temperature at which the?

A. saturated vapour pressure equals the atmospheric pressure
B. molecules leaves the liquid at a rate equal to the rate at which they return
C. molecules leave the liquid at a rate higher than that at which they return
D. molecules leave the liquid at a rate lower than the rate at which they return

Correct Answer: Option A

A. saturated vapour pressure equals the atmospheric pressure