d
Capacitance of each capacitor

\(C _{1}=\frac{ A 3 \epsilon_{0}}{\frac{1}{2}}=6 A \epsilon_{0}\)

\(C _{2}= A 4 E _{0}=4 A \in_{0}\)

Equivalent capacitance

\(C _{\text {eq }}=\frac{ C _{1} C _{2}}{ C _{1}+ C _{2}} \Rightarrow \frac{24}{10} A \in_{0}\)

\(q _{\text {net }}= C _{\text {eq }}(\Delta V ) \Rightarrow 240 A \in_{0}\)

\(\Delta V _{2}=\frac{240 A \epsilon_{0}}{4 A \epsilon_{0}}=60\,V\)

\(\left(\Delta V _{2}=\text { Potential drop across } C _{2}\right)\)

\(V _{\text {foil }}=60\,V\)