d
\(\mathrm{R}_{1}=\frac{\rho \mathrm{L}}{\mathrm{A}}\)

\(\mathrm{R}_{2}=\frac{(1.2 \rho)(1.2 \mathrm{L})}{\mathrm{A}}=\frac{1.44 \rho \mathrm{L}}{\mathrm{A}}\)

\(\mathrm{R}_{3}=\frac{(0.9 \mathrm{\rho })(0.9 \mathrm{L})}{\mathrm{A}}=\frac{0.81 \rho \mathrm{L}}{\mathrm{A}}\)

\(\mathrm{R}_{4}=\frac{\rho(1.5 \mathrm{L})}{\mathrm{A}}=\frac{1.5 \mathrm{\rho L}}{\mathrm{A}}\)

\(\therefore \)  \(\mathrm{R}_{3}<\mathrm{R}_{1}<\mathrm{R}_{2}<\mathrm{R}_{4}\)

For constant potential, \(\mathrm{P} \propto \frac{1}{\mathrm{R}}\)

\(\therefore P_{3} < P_{1} < P_{2} < P_{4}\)