Two computers communicate over a $20$ km optical fiber line with $250$ byte long frames at a transmission rate of $125$Mbps$.$ If the propagation speed in the environment is $2\backslash$times $10^8$ m$/$s and the probability of the frame being received incorrectly is $1\mathrm{.}5\%$

a$)$ Which error correction protocol should the sliding window protocol with a window width of $7$ frames work with? Why?

b$)$ Which error correction protocol should the sliding window protocol with a window width of $63$ frames work with? Why?