$39.$ Let C be a function defined by C$($v$)=357*$v$,$ where v is the velocity of the particle moving along a curve. At time t$=0,$ the velocity is y$=15.$ If the velocity of the particle increases at a constant rate of $6$ units per second, what is the rate of change of C with respect to time t$,$ at t $=8$ seconds. $($A$)-0\mathrm{.}765($B$)-0\mathrm{.}469($C$)-0\mathrm{.}374($D$)-0\mathrm{.}287$