Standard air is the:
a. Mass of 1 cubic meter of dry air at 20°C and atmospheric pressure
b. Mass of a cubic meter of air at atmospheric conditions
c. Volume of air at ambient temperature and atmospheric pressure
d. Volume of 1 kg of dry air at 21°C and atmospheric pressure at sea level or 101.325 kPa
e. Volume of 1 kg of air at 15°C and 100 kPa
Answer: D