A hollow conducting sphere of radius R has a charge $+Q$ as its outer surface. Inside the sphere at $r= \large\frac{R}{4}$ from its centre the value of electric potential will be :

$(A)\;zero \\ (B)\;\frac{1}{4 \pi \in _0}\frac{Q}{r} \\ (C)\; \frac{1}{4 \pi \in _0}\frac{Q}{r^2} \\ (D)\;\frac{1}{4 \pi \in _0}\frac{Q}{R}$

Inside a conducting sphere potential at each point is same as the potential at surface of sphere.
Hence D is the correct answer.