Let mass be m. The required to lift it is $F_2=mg$
$F_1$=force required to drag it along the plane
$f_1=mg \sin \theta+\mu mg \cos \theta$
$F_1 < F_2$
$mg \sin \theta +\mu mg \cos \theta < mg$
$\mu < \large\frac{1- \sin \theta}{\cos \theta}$
$\mu < \large\frac{1- \sin 30}{\cos 30}$
$\mu < \large\frac{1}{\sqrt 3}$
Hence d is the correct answer.