(d) Range of projectile $R = \frac{u^{2}\sin{2\theta}}{g}$
If $u$ and $\theta$ are constant then $R \propto \frac{1}{g}$
$\frac{R_{m}}{R_{e}} = \frac{g_{e}}{g_{m}} \Rightarrow \frac{R_{m}}{R_{e}} = \frac{1}{0.2} \Rightarrow R_{m} = \frac{R_{e}}{0.2} \Rightarrow R_{m} = 5R_{e}$