Explanation :
It is given that,
Speed of the electromagnetic wave, [tex]v=3\times 10^8\ m/s[/tex]
Wavelength, [tex]\lambda=0.6\ m[/tex]
We know that the relation between the speed, frequency and the wavelength is given by :
[tex]v=\nu \times \lambda[/tex]
[tex]\nu=\dfrac{v}{\lambda}[/tex]
[tex]\nu=\dfrac{3\times 10^8\ m/s}{0.6\ m}[/tex]
[tex]\nu=500000000\ Hz[/tex]
or
[tex]\nu=5\times 10^8\ Hz[/tex]
So, the correct option is (D).
Hence, this is the required solution.