A block is placed on a rough inclined plane of inclination $\theta=30 ^{\circ}$ . If the force to drag it along the plane is to be smaller than to lift it, the coefficient of friction $\mu$ should be less than

Question

\[(a)\;\frac{1}{2}\quad (b)\;\frac{\sqrt 3}{2} \quad (c)\;\frac{2}{3} \quad (d)\;\frac{1}{\sqrt 3} \]