Starting from rest at t $=0,$ a $5\mathrm{.}0-$kg block is pulled across a horizontal surface by a constant horizontal force having a magnitude of $12$ N$.$ If the coefficient of friction between the block and the surface is $0\mathrm{.}20,$ at what rate is the $12-$N force doing work at t $=5\mathrm{.}0$ s$?$

a$.$

$0\mathrm{.}13$ kW

b$.$

$0\mathrm{.}14$ kW