b
Velocity of the tennis ball on the surface of the earth or ground

\(\begin{array}{l}
v = \sqrt {\frac{{2gh}}{{1 + \frac{{{K^2}}}{{{R^2}}}}}} \,\,(where\,k = radius\,of\,gyration\\
of\,spherical\,shell\, = \sqrt {\frac{2}{3}} R)\\
Horizontal\,range\,AB = \frac{{{v^2}\sin 2\theta }}{g}\\
 = \frac{{{{\left( {\sqrt {\frac{{2gh}}{{1 + {k^2}/{R^2}}}} } \right)}^2}\sin \left( {2 \times {{30}^ \circ }} \right)}}{g}
\end{array}\)