c
(c) Total energy in \(SHM \) \(E = \frac{1}{2}m{\omega ^2}{a^2}\); (where \(a =\) amplitude)

Potential energy \(U = \frac{1}{2}m{\omega ^2}({a^2} - {y^2}) \)

\(= E - \frac{1}{2}m{\omega ^2}{y^2}\)

When \(y = \frac{a}{2}\)

\(⇒\) \(U = E - \frac{1}{2}m{\omega ^2}\left( {\frac{{{a^2}}}{4}} \right)\)

\(= E - \frac{E}{4} = \frac{{3E}}{4}\)