Answer: The correct answer is "microwave".
Step-by-step explanation:
Microwave is an electromagnetic wave. It falls in the range of electromagnetic spectrum between radio and infrared rays.
It is a high bandwidth communication. It is used in microwave oven for heating purpose and it is used in RADAR. Its frequency range lies between 300 MHz and 300 GHz.
When you speak into a cell phone, your sound waves must be converted into microwave in order to transmit the signal. The cell phone uses 800 MHz and 1900 MHz frequency range. It transmits and receives microwave.
Therefore, the correct option is "microwave".