The property which is not of an electromagnetic wave travelling in free space is that:

1. A
   they are transverse in nature.
2. B
   the energy density in electric field is equal to energy density in magnetic field.
3. C
   they travel with a speed equal to $\frac{1}{\sqrt{{\mu }_0{ϵ}_0}}$.
4. D
   they originate from charges moving with uniform speed.