An electromagnetic wave going through vacuum is described by

E = E₀ sin(κx – ωt); B = B₀ sin(κx – ωt)

Then

Explanation: The amplitudes of the electric and magnetic fields are

related as

…(i)

where c is the speed of wave and E₀ and B₀ are the amplitudes of the fields.

The speed of wave is related with its frequency and wavenumber as

…(ii)

where ω is the angular frequency of the wave ( and k is the wavenumber () and ν is the frequency and λ is the wavelength of the wave.

From (i) and (ii)

so A. is correct.

B. and C. are invalid relations. Only A. is the correct option.