ii$.$ The received FEC $75$ message block displayed below uses even parity checks,

with the parity bits displayed at the end of each row $($A$-$E$)$ and column $(1-7)$ in the

shaded cells $($see Section $3\mathrm{.}7\mathrm{.}1).$ A single bit error has occurred somewhere in this

message block.

By checking each row and column, determine the row$-$column grid reference of

the bit error.

$-$What change needs to be made to correct the error?

As part of your answer, briefly explain how you located the bit error.