The AM radio wave bends appreciably round the corners of a $1m \times 1m$ board but the FM wave only negligibly bands. If the average wavelength of the AM and FM waves are $\lambda_a$ and $\lambda_f$ , then

Question

$\begin {array} {1 1} (a)\;\lambda_a > \lambda_f & \quad (b)\;\lambda_a = \lambda_f \\ (c)\;\lambda_a < \lambda_f & \quad (d)\;\text{ can't be determined} \end {array}$