A team needs to deploy resources using Azure Resource Manager templates. You have to ensure the security for the users performing the deployment. They cannot view the connection strings required by the application being deployed via the template. Which of the following would you use for this requirement?

Answer options:

A.A parameter file
B.A Storage account
C.Azure Key vault
D.Web.config file

Answer – C 
The ideal service to use for this purpose is the Azure Key Vault service. The Microsoft documentation mentions the following. 

All other options are incorrect since the ideal service to use for this requirement is the Azure Key Vault service. 
For more information on using the Azure Key Vault service to protect application secrets, please visit the below URL- 

https://docs.microsoft.com/en-us/azure/architecture/multitenant-identity/key-vault