The wavelength of a wave is given by the formula:
wavelength = speed of light / frequency
where the speed of light is approximately 3 x 10^8 m/s.
Substituting the given frequency of 3 x 10^9 Hz, we get:
wavelength = (3 x 10^8 m/s) / (3 x 10^9 Hz) = 0.1 meters
Therefore, the wavelength for radio waves with frequency 3 x 10^9 Hz is 0.1 meters.
So the answer is option A: 1 x 10^-1 m.