A sinusoidal electromagnetic plane wave travels through the empty space in $x$ - direction. The electric wave is polarized in the $y$ - direction frequency of waves is $1.5\: GHz$. At a certain point $P$ in space, the oscillating $E_y$ attains a maximum magnitude $E_o = 6.3 \: mV/m$ \[\] The maximum magnitude $B_o$ of the magnetic field at the point is

Question

$\begin {array} {1 1} (a)\;2.1 \times 10^{-7}T & \quad (b)\;0.14 \times 10^{-7}T \\ (c)\;1.4 \times 10^{-5}T & \quad (d)\; 2.1 \times 10^{-5}T \end {array}$