# The magnetic field in a plane electromagnetic wave is given by $B_y= 2 \times 10^{-7} \: \sin (0.5\times10^3x+1.5\times10^{11}t)T$ The wavelength and frequency of the wave are
$\begin {array} {1 1} (a)\;0.26\: m \: and \: 239 \: MHz & \quad (b)\;1.26\: cm \: and \: 23.9 \: GHz \\ (c)\;1.26\: m \: and \: 23.9 \: MHz & \quad (d)\;0.26\: cm \: and \: 2.39 \: GHz \end {array}$