Which protocol is lightweight?a.HTTPb.MQTTc.CoAPd.SPI

The lightweight protocol among the options given is MQTT (Message Queuing Telemetry Transport).

Here's why:

a. HTTP (Hypertext Transfer Protocol) - This is not considered lightweight as it is a heavy-duty protocol used for transmitting hypertext over the internet.

b. MQTT (Message Queuing Telemetry Transport) - This is a lightweight messaging protocol for use on top of the TCP/IP protocol. It is designed for connections with remote locations where a small code footprint is required or the network bandwidth is limited.

c. CoAP (Constrained Application Protocol) - This is also a lightweight protocol, but it's not as lightweight as MQTT. It's