Electric Potential & Equipotentials question from NEET 2021

Answer: (c)

1. Connected spheres reach the same potential: $\frac{kq_1}{R_1} = \frac{kq_2}{R_2} \Rightarrow \frac{q_1}{q_2} = \frac{R_1}{R_2}$
2. $\frac{\sigma_1}{\sigma_2} = \frac{q_1/4\pi R_1^2}{q_2/4\pi R_2^2} = \frac{R_1}{R_2}\cdot\frac{R_2^2}{R_1^2} = \frac{R_2}{R_1}$
3. So the answer is (c) $\frac{R_2}{R_1}$.