$Torr$ is the unit of

$1 \, g = \dots \, a.m.u.$

$1 \text{ MW} = \dots \text{ erg/s}$.

Candela is the unit of

Given below are two statements:
Statement $I$: Astronomical unit $(AU)$,Parsec $(pc)$,and Light year $(ly)$ are units for measuring astronomical distances.
Statement $II$: $AU < pc < ly$
In the light of the above statements,choose the most appropriate answer from the options given below:

What is a system of units? Write the different types of systems of units.