What technology is primarily used to transmit information about a product's contents in real-time?

Radio Frequency Identification (RFID) is the correct answer because it utilizes electromagnetic fields to automatically identify and track tags attached to objects, such as products. These RFID tags contain electronically stored information, which can be read by RFID readers, allowing for real-time monitoring of a product's contents and its movement through the supply chain.

RFID technology can collect data without the need for direct line-of-sight, making it more efficient and flexible compared to other technologies like barcode scanning, which requires a scanner to directly line up with a barcode. RFID provides advantages in speed and accuracy, enabling businesses to maintain up-to-date inventory and logistics information efficiently.

Other techniques, such as manual tracking, lack the automation and real-time capabilities offered by RFID. While optical character recognition can read printed text, it does not transmit real-time information about product contents in the same way RFID does. Thus, RFID stands out as the technology best suited for this purpose in the context of modern inventory and supply chain management.