Near Field Communication (NFC) is the correct answer because it is a set technology that allows smartphones and other devices to communicate with each other when they are close together or touching. This is typically used in contactless payment systems, card emulations, and simple peer-to-peer data transfer. Bluetooth is incorrect because although it's used for wireless communication, it's generally used for longer ranges and doesn’t support the quick and secure communication required for contactless payments. RFID, while similar in some regards to NFC, usually pertains to identification and tracking, which doesn't involve two-way communication between devices like payment transactions. WiFi and Infrared are not suitable for the close proximity requirements of contactless payments and their functionalities and usages are different from what is needed in this scenario.