$1)$ Explain how a source station A and a destination station B recover from the following error conditions for each of the cases stated below. State the possible outcomes and how the problem is resolved in each: $[4+4+4-12]$

a$)$ A and B are using Go$-$Back$-$N ARQ with W$-7$ and sends frames $0,1,2,$ and $3$ of which B receives frames $0,1,$ and $3,$ i$.$e$.,$ Frame$-2$ is lost. B sends REJ$-2$ but REJ$-2$ is lost.

b$)$ A and B are using Go$-$Back$-$N ARQ with W$-4$ and sends frames $0,1,2,3$ of which B receives frames $0,1,$ and $2,$ i$.$e$.,$ Frame$-3$ is lost in transmission.

c$)$ A and B are using Selective$-$Reject ARQ with W$-4$ and sends frames $0,1,$ and $2$ of which B receives frames $0$ and $2,$ i$.$c$.,$ Frame$-1$ is lost in transmission that is detected by B$.$ B sends SREJ$-1$ but SREJ$-1$ is lost.