( A ) $a = \frac{\lambda^2}{L} $ and $b_{min} = \sqrt{4 \lambda L}$
( B ) $a = \frac{\lambda^2}{L} $ and $b_{min} = (\frac{2 \lambda^2}{L})$
( C ) $a = \sqrt{ \lambda L} $ and $b_{min} = (\frac{2 \lambda^2}{L})$
( D ) $a = \sqrt{ \lambda L} $ and $b_{min} = \sqrt{4 \lambda L}$