$A$ plane electromagnetic wave travels in free space along the $x$-direction. The electric field component of the wave at a particular point of space and time is $E = 6 \; Vm^{-1}$ along the $y$-direction. Its corresponding magnetic field component, $B$, would be:

• A
  $2 \times 10^{-8} \; T$ along the $z$-direction
• B
  $6 \times 10^{-8} \; T$ along the $x$-direction
• C
  $6 \times 10^{-8} \; T$ along the $z$-direction
• D
  $2 \times 10^{-8} \; T$ along the $y$-direction