Final answer:
WiMAX is the technology that refers to a long-distance line-of-sight Internet service, distinct from short-range technologies such as Wi-Fi, Bluetooth, and infrared.
Step-by-step explanation:
The answer that refers to a long-distance line-of-sight Internet service is a. WiMAX. WiMAX stands for Worldwide Interoperability for Microwave Access and is a wireless communication standard designed to provide high-speed broadband access over long distances. Using microwaves for transmission, WiMAX requires a clear line of sight between the transmitter and receiver which is vital due to the short wavelengths involved. This technology is very different from IEEE 802.11 (commonly known as WiFi), which is designed for shorter distances, typically within a home or building. IR (infrared) and Bluetooth also operate over much shorter distances, the latter commonly for connecting devices such as headphones or hands-free systems to cell phones.