Which of the following does not reduce friction

a)ball bearing
b)lubricant
c)rolling
d)grooving and treading

Dear Student,

Making grooves in the shoes increases friction.
Polishing rough surfaces makes it smooth, thus reducing friction. 
Wheels and ball bearings create rolling friction which has the least magnitude compared to sliding and static friction.
Air cushion makes a layer of air between two surfaces, which helps in reducing friction

 Regards,
Daivik Lakshmipathy.