Sky wave propagation is suitable for radio waves in the frequency range of:

Solution

1. Sky wave propagation uses the ionosphere to reflect radio waves back to Earth.
2. Frequencies below 2 MHz are mostly absorbed by the D-layer of the ionosphere.
3. Frequencies above 30 MHz generally penetrate the ionosphere and escape into space.
4. The effective range for ionospheric reflection is 2 MHz to 30 MHz.
5. Hence the answer is (A).