a
\(\Rightarrow g(h)=\frac{g}{\left(1+\frac{h}{R}\right)^2}\)

\(\therefore \frac{g}{4}=\frac{g}{\left(1+\frac{h}{R}\right)^2}\)

\(\therefore 4=\left(1+\frac{h}{R}\right)^2\)

\(\therefore 2=1+\frac{h}{R}\)

\(\therefore \frac{h}{R}=1 \quad \ldots(1)\)

\(\Rightarrow g(d)=g\left(1-\frac{d}{R}\right)^2\)

\(\therefore \frac{g}{4}=g\left(1-\frac{d}{R}\right)^2\)

\(\therefore \frac{1}{4}=1-\frac{d}{R}\)

\(\therefore \frac{d}{R}=1-\frac{1}{4}\)

\(\therefore \frac{d}{R}=\frac{3}{4} \quad \ldots(2)\)

\(\therefore\) Taking ratio of equ.\((1)\) and \((2)\)

\(\frac{h}{d}=\frac{4}{3}\)