Assertion (A): Shafts supporting helical gears must have only deep groove ball – bearings.
Reason (R): Helical gears produce axial thrusts.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true