Two nodes in a local area network forward frames of $1000-$bits.

The propagation time between the two nodes is $2$ times the

transmission time.

If the two stations use stop$-$and$-$wait, what will be the maximum line

efficiency?

$($a$)50\%$

$($b$)1000$

$($c$)100\%$

$($d$)1\%$

In this case if the two stations use sliding window protocol, the

maximum line efficiency will be up to:

$($a$)100\%$

$($b$)10\%$

$($c$)90\%$

$($d$)1$