The correct answer is A. UNII.
The Unlicensed National Information Infrastructure (UNII) bands are three frequency bands in the ISM band that are allocated by the Federal Communications Commission (FCC) for unlicensed use. The UNII bands are 5.15â5.25 GHz, 5.25â5.35 GHz, and 5.47â5.725 GHz.
The UNII bands are used for a variety of wireless applications, including Wi-Fi, Bluetooth, and wireless personal area networks (WPANs). The UNII bands are also used for some industrial, scientific, and medical (ISM) applications.
The UNII bands are unlicensed, which means that anyone can use them without having to obtain a license from the FCC. This makes the UNII bands a popular choice for wireless applications, as they are relatively easy to set up and use.
The UNII bands are also relatively interference-free, as they are not used by many other types of wireless devices. This makes them a good choice for applications that require high data rates or low latency.
However, the UNII bands are also subject to some restrictions. For example, the maximum power that can be used in the UNII bands is limited. Additionally, some types of wireless devices are not allowed to use the UNII bands.
Overall, the UNII bands are a good choice for a variety of wireless applications. They are unlicensed, interference-free, and relatively easy to set up and use. However, there are some restrictions on their use that should be considered before using them.
The other options are incorrect for the following reasons:
- B. Unlicensed PCS is a band of spectrum that is allocated by the FCC for unlicensed use. However, it is not part of the ISM band.
- C. Millimetre wave is a type of radio wave that has a very short wavelength. It is not used in the ISM band.
- D. Bluetooth is a wireless technology that is used to connect devices over short distances. It is not used in the ISM band.