The correct answer is appinstance.westus2.azurecontainer.example.com.

When you set a DNS label for an Azure Container Instance that label becomes the leftmost subdomain and Azure includes the region as the next subdomain to form the fully qualified domain name. In this case the DNS label appinstance combined with the westus2 region yields the host name appinstance.westus2.azurecontainer.example.com.

Cloud Run is incorrect because Cloud Run is a Google Cloud product for running containers and it does not define the Azure Container Instance naming scheme.

azurecontainer.example.com/appinstance is incorrect because that shows the DNS label as a path component rather than a subdomain and Azure Container Instances expose the label as part of the host name not as a URL path.

appinstance.azurecontainer.example.com is incorrect because it omits the region segment that Azure includes in the FQDN for container instances.

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