$A$ plane electromagnetic wave travelling along the $X-$ direction has a wavelength of $3\, mm$. The variation in the electric field occurs in the $Y-$ direction with an amplitude of $66\, Vm^{-1}$. The equations for the electric and magnetic fields as a function of $x$ and $t$ are respectively:

• A
  $E_y = 33\cos(\pi \times 10^{11}(t - x/c))$,$B_z = 1.1 \times 10^{-7}\cos(\pi \times 10^{11}(t - x/c))$
• B
  $E_y = 11\cos(2\pi \times 10^{11}(t - x/c))$,$B_z = 11 \times 10^{-7}\cos(2\pi \times 10^{11}(t - x/c))$
• C
  $E_x = 33\cos(\pi \times 10^{11}(t - x/c))$,$B_z = 11 \times 10^{-7}\cos(\pi \times 10^{11}(t - x/c))$
• D
  $E_y = 66\cos(2\pi \times 10^{11}(t - x/c))$,$B_z = 2.2 \times 10^{-7}\cos(2\pi \times 10^{11}(t - x/c))$