A Parcel of Air at 25 $\degree$ C Is Completely Saturated with a Vapor Pressure of 30

A parcel of air at 25 $\degree$ C is completely saturated with a vapor pressure of 30 mb.Cloud formation removes water vapor from the atmosphere resulting in a new vapor pressure of 15 mb at the same temperature of 25 $\degree$ C.What is the relative humidity of the parcel of air at 25 $\degree$ C and
15 mb?

A) 15 mb
B) 50%
C) 50 mb
D) 15%