D. Zigbee Explanation: George employed a short-range communication protocol based on the IEEE 203.15.4 standard, which is used in devices that transfer data infrequently at a low rate in a restricted area, within a range of 10-100 m. Zigbee is a wireless communication technology that is designed for low-power, low-data-rate applications, and it operates on the IEEE 203.15.4 standard. Zigbee uses mesh networking, which means that each device in the network can act as a repeater to extend the network's range. This makes Zigbee an ideal technology for industrial systems that require secure and reliable communication over short distances.

A. LPWAN: Low Power Wide Area Network (LPWAN) is designed for long-range communications at a low bit rate. It is not based on IEEE 802.15.4, so this option does not match the scenario. B. MQTT: MQTT stands for Message Queuing Telemetry Transport. It is a messaging protocol often used for the Internet of Things (IoT). It is not a wireless communication technology itself, but rather a protocol that can be used on top of various communication systems. C. NB-IoT: Narrowband IoT (NB-IoT) is a standards-based low power wide area (LPWA) technology developed to enable a wide range of new IoT devices and services. NB-IoT is not based on IEEE 802.15.4; it uses a different standard. D. Zigbee: Zigbee is a specification for a suite of high-level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks. Zigbee is typically used in low data rate applications that require long battery life and secure networking.

D. Zigbee

D. Zigbee

The correct option is D. Zigbee

D. Zigbee like 312-50v11 246 CEH BOOK Module 16 P2372 802.15.4 (ZigBee): The 802.15.4 standard has a low data rate and complexity.