A particle performing uniform circular motion has angular momentum $L$., its angular frequency is doubled and its $K . E$. halved, then the new angular momentum is
$\{\mathrm{A}\} 1 / 2$
\{B $\} 1 / 4$
$\{\mathrm{C}\} 2 \mathrm{~L}$
$\{\mathrm{D}\} 4 \mathrm{~L}$