What are the four frequency bands used in communication?

The correct answer identifies the four frequency bands used in communication as HF, VHF low, VHF high, and UHF. Each of these bands serves distinct roles in radio communication, television broadcasting, and other forms of wireless transmission.

HF, or High Frequency, ranges from 3 to 30 MHz and is primarily used for long-distance communication because it can reflect off the ionosphere. VHF low and VHF high are subdivisions of Very High Frequency, which range from 30 MHz to 300 MHz. These bands are commonly used for FM radio and television broadcasts. UHF, or Ultra High Frequency, extends from 300 MHz to 3 GHz and is used for various communications, including television signals and mobile phone transmissions.

The other options, while they involve different aspects of communication technologies, do not accurately categorize frequency bands in the conventional sense. For example, AM and FM refer to types of modulation used in broadcasting but do not represent frequency bands. The designations of low, ultra-low, high, and super high are vague and not standard terminology in communication frequency bands. Lastly, 1G through 4G refer to generations of mobile technology, which are more about advancements in technology than specific frequency bands. Thus, the correct choice