When the vapor pressure of a liquid is equal to the atmospheric pressure, the liquid O has no observable changes
O boils vigorously
O begins to boil
O evaporates

O begins to boil

Explanation:

When the vapor pressure of a liquid is equal to the atmospheric pressure, the liquid suddenly begins to boil.

At this point the boiling point of the liquid has been reached. Further addition of heat energy will cause the liquid to boil vigorously Subsequently evaporation will start from the surface of the boiling liquid.The atmospheric pressure is the ambient pressure measured with the respect to the sea level pressure.

The answer is b i think