Answer: D. Mole
Explanation: A unit is defined as the standard of reference chosen to measure any physical quantity.
A. Kilogram is the S.I unit of mass.
B. Ampere is the S.I unit of electric current
C. Kelvin is the S.I unit of temperature.
D. Mole is the S.I unit of mole of a substance. A mole is the amount of substance which contains as any elementary entities as there are atoms in 0.012 kg of carbon-12.
