A communication link uses circuit switching technology to transmit

a message of $5{10}^4$ bytes. Assume the length of the line is $100km,$

the velocity of propagation is ${10}^8\frac{m}{s}$ and the data rate is $100Mbps.$

The maximum efficiency in this case is:

$($a$)580\%$

$($b$)100\%$

$($c$)50\%$

$($d$)$ neither $a,b$ or $c$