b
Distance between two cities \(=150\, \mathrm{km}\)

Resistance of the wire, \(R=\left(0.5\, \Omega \,\mathrm{km}^{-1}\right)(150 \,\mathrm{km})=75 \,\Omega\)

Voltage drop across the wire,

\(V=\left(8 \,\mathrm{V} \mathrm{km}^{-1}\right)(150 \,\mathrm{km})=1200 \,\mathrm{V}\)

Power loss in the wire is

\(P=\frac{V^{2}}{R}=\frac{(1200\, \mathrm{V})^{2}}{75\, \Omega}=19200 \,\mathrm{W}=19.2\, \mathrm{kW}\)