The correct answer is A. NFC (Near Field Communication).

According to the CompTIA A+ Core 1 220-1201 objectives under Mobile Devices, NFC is commonly used for short-range wireless communication between devices. In the context of mobile printing:

NFC-enabled printers allow a user to tap a mobile device (phone or tablet) to the printer to initiate a print job instantly without needing to configure Wi-Fi credentials or use cables.

This is particularly common in mobile-friendly environments like offices or public kiosks.

Why the other options are incorrect:

B. Hotspot: Provides an Internet connection, not a direct mobile-to-printer interface.

C. Infrared: Legacy technology largely replaced by NFC and Wi-Fi; rarely used in modern printers.

D. USB: Requires a wired connection, not suitable for sending a print job wirelessly from a mobile device.