c
In general we have assumed \(\mu=1.5\) So, \(\mathrm{f}=20\, \mathrm{cm}\)

\(\frac{1}{f}=\frac{1}{v}+\frac{1}{u}\)

\(\frac{1}{20}=\frac{1}{v}+\frac{1}{30}\)

\(\frac{1}{v}=\frac{1}{20}-\frac{1}{30}=\frac{10}{600}\)

\(v=60\, \mathrm{cm}\)

\(\frac{\mathrm{h}_{\mathrm{i}}}{\mathrm{h}_{\mathrm{o}}}=2\)

\(h_{i}=2 \times\left|h_{0}\right|\)

\(\mathrm{h}_{\mathrm{i}}=4 \,\mathrm{cm}\)

Here, image is real, inverted, magnified field and height of image is \(4 \,\mathrm{cm}\)