A uniform disc of mass m and radius r is rolling without slipping up a rough inclined plane which makes an angle 300 with the horizontal.if the coefficient of static and kinetic friction are each equal to mu and the only force action on the disc are gravitational and frictional force then find the direction and magnitude of the frictional force acting on it.
a.mg/6 down the incline
b.mg/6 up the incline
c.mg/3 down the incline
d.mg/3 up the incline.