d
\(\begin{gathered}
\,I\,\, = \,\,\frac{{m{L^2}}}{{12}}\,\,\,\,\,\therefore \,\,I'\,\, = \,\,4\,\,\left[ {\frac{{m{L^2}}}{{12}}\,\, + \;\,\frac{{m{L^2}}}{4}} \right] \hfill \\
I'\,\, = \,\,4\,\,\left[ {\frac{{m{L^2}}}{3}} \right]\,\, = \,\,\frac{4}{3}\,\,M{L^2}\,\,\,\therefore \,\,m{L^2}\,\, = \,\,12I \hfill \\
I'\,\, = \,\,\frac{4}{3}\,\, \times \,\,12I\,\, = \,\,16I \hfill \\
\end{gathered} \)