This question considers process scheduling in an operating system.

i$.$Briefly describe what is meant by round$-$robin scheduling.

Four processes $$ A$,$ B$,$ C and D $$ are ready to execute, having arrived in that order. They require different numbers of quanta to complete and request different priorities $(1$ is lowest, $4$ is highest$)$:

Process A requires $2$ quanta, requested priority $1$

Process B requires $4$ quanta, requested priority $4$

Process C requires $5$ quanta, requested priority $2$

Process D requires $3$ quanta, requested priority $3.$