The electric field for an electromagnetic wave in free space is $\overrightarrow{\mathrm{E}}=\overrightarrow{\mathrm{i}}30 \cos \left(\mathrm{kz}-5 \mathrm{x} {10}^8\mathrm{t}\right)$, where magnitude of E is in V/m. The magnitude of wave vector, k is (velocity of EM wave in free space = 3×10⁸m/s)

• A

  0.46 rad m^–1

• B

  3 rad m^–1

• C

  1.66 rad m^–1

• D

  0.83 rad m^–1