You have an Azure app service application which needs to be deployed to two regions to achieve higher availability. You are using Azure DevOps for continuous integration and delivery and ARM templates task in Azure pipelines to deploy the infrastructure as code. 
You need to ensure that secure values like passwords are not added directly to your ARM template.You are using a single pipeline for the deployment to both regions. Deployment to region A has different secret values from region
B. Even both regions have different subscriptions.You are using the Azure Key Vault to pass secure parameter value during deployment. 
What is the recommended approach for the secret values in Key Vault? Choose an option from below.

Answer options:

A.Using a parameter file
B.Using appliance resource provider
C.Using a nested template
D.Using Azure Key Vault task

Answer: C 

https://docs.microsoft.com/en-us/learn/modules/configure-and-manage-azure-key-vault/
https://docs.microsoft.com/en-us/learn/modules/configure-and-manage-azure-key-vault/
https://docs.microsoft.com/en-us/azure/azure-resource-manager/templates/key-vault-parameter
https://docs.microsoft.com/en-us/azure/azure-resource-manager/templates/key-vault-parameter