An IoT Company Has Rolled Out a Fleet of Sensors

Multiple Choice

An IoT company has rolled out a fleet of sensors for monitoring temperatures in remote locations. Each device connects to AWS IoT Core and sends a message 30 seconds, updating an Amazon DynamoDB table. A System Administrator users AWS IoT to verify the devices are still sending messages to AWS IoT Core: the database is not updating. What should a Solutions Architect check to determine why the database is not being updated?

A) Verify the AWS IoT Device Shadow service is subscribed to the appropriate topic and is executing the AWS Lambda function.
B) Verify that AWS IoT monitoring shows that the appropriate AWS IoT rules are being executed, and that the AWS IoT rules are enabled with the correct rule actions.
C) Check the AWS IoT Fleet indexing service and verify that the thing group has the appropriate IAM role to update DynamoDB.
D) Verify that AWS IoT things are using MQTT instead of MQTT over WebSocket, then check that the provisioning has the appropriate policy attached.