Which infrared-based standard enables data transfer between devices using line-of-sight communication?

• A. Bluetooth
• B. Near Field Communication (NFC)
• C. Radio Frequency Identification (RFID)
• D. Infrared Data (IrDA)

Answer: (D)

IrDA, the infrared-based standard, enables data transfer between devices when they are aimed at each other using infrared light and a direct line-of-sight path. This family of protocols defines how infrared transceivers negotiate and exchange data over short distances, with the requirement that nothing blocks the infrared beam. Because it relies on visible-to-infrared light, direction and alignment matter, and speeds vary across different IrDA modes from slower to faster infrared transfers. In contrast, Bluetooth, NFC, and RFID rely on radio waves and do not require the same line-of-sight or infrared signaling, which is why they are not the infrared, line-of-sight data transfer standard.