Which of the following sentences explain the difference between tail$-$drop and random early detection $($RED$)$ as drop policies for a router output port.O a$.$ Tail$-$drop discards packets when the Output port's buffer is full, while RED selectively drops packetsbefore congestion becomes severeO b$.$ Tail$-$drop uses a weighted random algorithm to drop packets, while RED drops packets based on apredetermined threshold c$.$ None of the choicesO d$.$ Tail$-$drop and RED are two names for the same drop policy; they have no significant differences