A box of mass `2 kg` is placed on the roof of a car. The box would remain stationary until the car attains a maximum acceleration. Coefficient of static friction between the box and the roof of the car is `0.2 and g = 10 ms^(-2)`. The maximum acceleration of the car, for the box to remain stationary, is
Options:
(a) `8 ms^(-2)`
(b) `6 ms^(-2)`
(c) `4 ms^(-2)`
(d) `2ms^(-2)`