The correct answer is D. MCU.
An IoT endpoint is a device that collects data from the physical world and sends it to the cloud for processing. The four main components of an IoT endpoint are:
- Sensor: A sensor is a device that converts a physical quantity into an electrical signal. For example, a temperature sensor converts the temperature of the environment into an electrical signal.
- Actuator: An actuator is a device that converts an electrical signal into a physical action. For example, a motor is an actuator that converts an electrical signal into mechanical motion.
- Communication module: A communication module is a device that allows the IoT endpoint to communicate with other devices. For example, a Wi-Fi module allows the IoT endpoint to connect to the internet.
- Microcontroller (MCU): An MCU is a small computer that controls the operation of the IoT endpoint. The MCU is responsible for collecting data from the sensors, processing the data, and sending the data to the cloud.
The MCU is not a necessary component of an IoT endpoint. In some cases, the data can be collected and processed by a cloud-based service. However, the MCU is often used in IoT endpoints because it allows the device to be more autonomous. The MCU can store data locally, process the data locally, and make decisions locally. This can be important in cases where there is no internet connection or where the internet connection is unreliable.
In conclusion, the correct answer is D. MCU. The MCU is not a necessary component of an IoT endpoint, but it is often used in IoT endpoints because it allows the device to be more autonomous.