Solve this:

​Q9. A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6 V m^–1, what is the magnetic field vector at that point?

      (1) 2 × 10^–8 T                                (2) $\frac{1}{2}\times {10}^{-8} \mathrm{T}$


      (3) 2 T                                            (4) $\frac{1}{2}\mathrm{T}$