A $1,000$ KVA transformer has $2,500$ watts iron loss, and $11,000$ watts copper loss at full load. The power factor is $0\mathrm{.}85$ lagging. Calculate the all$-$day efficiency of the transformer at daily load cycle of $14$ hours half load and $10$ hours full load.

$($a$)97\mathrm{.}32\%$

$($b$)98\mathrm{.}58\%$

$($c$)99\mathrm{.}20\%$

$($d$)99\mathrm{.}75\%$