Let the velocity vector $bev(t)=($:$5t^4,-12sin(3t),6$exp$(3t)$:$).$ Compute the acceleration vector $a(t).$

$A.($:$60t^2,108sin(3t),54$exp$(3t)$:$)$

$B.($:$20t^3,-(36cos(3t)),18$exp$(3t)$:$)$

$C.($:$60t^2,108sin(3t),54$exp$(3t)$:$)+($:$1,1,5$:$)$

$D.($:$t^5,4cos(3t),2$exp$(3t)$:$)+($:$1,-3,3$:$)$

$E.($:$t^5,4cos(3t),2$exp$(3t)$:$)$