Final answer:
Azure IoT Hub is the managed service that provides bidirectional communication between an IoT device and Azure.
Step-by-step explanation:
The managed service that provides bidirectional communication between an IoT device and Azure is Azure IoT Hub. Azure IoT Hub is a cloud-based service that enables secure and scalable bidirectional communication between IoT devices and cloud applications. It acts as a central hub for connecting, provisioning, and managing billions of IoT devices.