Frame $0,$ Frames $1$ and $2$ are sent; frames $0$ &$1$ arrived save and frame $2$ is lost.

Frames $3$ and $4$ are sent; all frames arrived save But the acknowledgement is delayed.

Frames $5,6,$ and $7$ sent; Frames $5,7,$ arrived save and frame $6$ lost.

Repeat step $3$ with selective reject ARQ protocol, Frames $5,6,$ and $7$ sent; Frames $5,7,$ arrived save and frame $6$ lost.

Which protocol Go$-$back$-$N ARQ protocol OR selective reject ARQ protocol you prefer in answering step $3$ & $4$ and what is your justification