What technology enables secure and contactless payment transactions using a PoS machine?

The correct answer is NFC (Near Field Communication) because it is specifically designed for secure, short-range communication between devices, including payment systems. NFC technology allows users to tap their mobile devices or contactless cards on a Point of Sale (PoS) terminal to complete transactions without the need for physical contact. This capability enhances convenience and speeds up the payment process while maintaining a level of security through encryption and other protective mechanisms.

In the context of contactless payments, NFC is particularly effective due to its quick connectivity—enabling communication within a few centimeters—making it ideal for scenarios like retail payments where speed and convenience are key. Additionally, NFC incorporates security features that protect transaction data, further reinforcing its use in financial transactions.

Other technologies mentioned may relate to communication or security, but they do not specifically provide the same level of functionality for contactless payments. For example, Bluetooth is a wireless technology that can also be used for payments but typically requires more setup steps compared to NFC. SAE is focused on secure authentication between devices but is not specifically aimed at transaction processing. GCMP is a protocol used for encryption and ensuring the integrity of data but does not facilitate the contactless aspect necessary for immediate payment transactions like NFC does.