Problem $17$

Two air$-$filled capacitors are connected in parallel arrangement; $C_1=3F$ and $C_2=5F.$ They are charged with a battery $12$ V $.$ Then the battery is disconnected. After that, the second capacitor only is filled with a dielectric material with $=2\mathrm{.}5.$ Thus the final potential difference across the first capacitor would be:

a$)3\mathrm{.}1$ V

b$)6\mathrm{.}2$ V

c$)9\mathrm{.}3$ V

d$)12$ V

c$)15\mathrm{.}5$ V