Correct option is D
Absolute pressure:- It is defined as the pressure which is measured with reference to absolute vaccum pressure.
Gauge pressure:- It is defined as the pressure which is measured with the help of a pressure measuring instrument, in which the atmospheric pressure is taken as datum.
Vacuum pressure:- It is defined as the pressure below the atmospheric pressure. The relationship between the above pressures is given as,
1) Absolute pressure Atmospheric pressure + Gauge pressure
Pabs = Patm + Pgauge
2) Vacuum pressure = Atmospheric pressure -
Absolute pressure
Pvacuum = Patm - Pabs
