A conducting spherical shell is earthed. A +ve charge $+q_1$ is placed at its centre and another +ve charge $+q_2$ is placed outside at a distance d from centre . If the conducting spherical shell is not earthed , then force on $q_2$ is:

Question

$(A)\;zero \\ (B)\;\frac{q_1q_2}{4 \pi \in_0 d^2} \\ (C)\; \frac{q_1q_2}{4 \pi \in_0 (d-R)^2} \\ (D)\;\frac{q_1q_2}{4 \pi \in_0 (d^2-R^2)} $