Which communication type allows two devices to communicate by bringing them within 2 inches of each other?

The correct choice is NFC (Near Field Communication) because NFC is specifically designed for communication between devices that are in very close proximity—typically within 2 inches of one another. This short-range technology is commonly utilized for secure transactions, data exchange, and connection initiation. Its functionality makes it ideal for things like mobile payments and tapping to connect devices, as it ensures that only devices that are intentionally brought very close together can engage in communication.

In contrast, Bluetooth connects devices over longer distances, typically ranging from about 30 feet to several hundred feet depending on the version and implementation. This makes Bluetooth suitable for wireless audio devices, keyboards, and other peripherals, but it does not provide the same level of security or proximity requirement as NFC.

Ethernet is a wired connection method primarily used for networking computers and devices over a local area network (LAN). It requires physical cabling and does not operate wirelessly or over short distances like NFC.

WiFi allows for wireless internet connectivity over much greater distances than NFC, usually spanning several hundred feet, making it ineffective for the close-range communication scenario described in the question.

Thus, NFC stands out due to its unique capability for very short-range communication, fulfilling the requirement of the question.