Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication ?

A is transmitted through ground wave, B via sky wave and C via space wave

For ground wave propagation, the frequency range is 530 kHz to 1710 kHz. For sky wave propagation, the frequency range is 1710 kHz to 40 MHz. For space propagation, the frequency range is 54 MHz to 4.2 GHz. Thus, option (b) is correct.