A thin uniform rod of length l and mass m is   swinging freely about a horizontal axis passing  through its end. Its maximum angular speed is $\omega$  . Its centre of mass rises to a maximum height

• A

  $\frac{l^2 {\omega }^2}{ g}$

• B

  $\frac{l^2 {\omega }^2}{6 g}$

• C

  $\frac{l^2 {\omega }^2}{3 g}$

• D

  $\frac{l^2 {\omega }^2}{5 g}$