Which statement is true regarding direct methods in Azure IoT?

Direct methods in Azure IoT are a powerful way for back-end applications to invoke commands on IoT devices. The correct choice highlights that direct methods require parameters to be specified by the back-end application to function. This is essential because direct methods often carry specific commands or data that need to be sent to the device for it to perform a certain action. Without these parameters, the device wouldn't know what it is being instructed to do, which demonstrates the necessity of precise command structure from the back-end app.

The other options do not accurately represent how direct methods operate. They aren't exclusive to the device itself, as they are explicitly initiated by back-end applications. Additionally, while direct methods can interact with device twins, they are not automatically synchronized with them; any synchronization needs to be managed separately. Lastly, back-end applications are indeed necessary for direct methods, contradicting the notion that they can function independently.