Solution

MQTT (Message Queuing Telemetry Transport) is a lightweight, publish-subscribe network protocol that is commonly used in IoT (Internet of Things) devices. It is designed for low-bandwidth, high-latency, or unreliable networks, making it ideal for communication between IoT devices. a) HTTP : While HTTP is used for general web communication, it is too heavy for resource-constrained IoT devices. b) FTP : FTP is used for file transfer over a network, not for continuous IoT device communication. d) IMAP : IMAP is used for retrieving emails from a mail server, irrelevant in the context of IoT communication. e) SMTP : SMTP is used for sending emails, not for device communication in IoT networks.