You need to ensure that clients are able to access the …

Your company has a subscription to Azure.
You configure your contoso.com domain to use a private Certificate Authority. You deploy a web site named
MyApp by using the Shared (Preview) web hosting plan.
You need to ensure that clients are able to access the MyApp website by using https.
What should you do?

A.
Back up the Site and import into a new website.

B.
Use the internal Certificate Authority and ensure that clients download the certificate chain.

C.
Add customdomain SSL support to your current web hosting plan.

D.
Change the web hosting plan to Standard.

Explanation:
Enabling HTTPS for a custom domain is only available for the Standard web hosting plan mode of Azure
websites.
https://azure.microsoft.com/en-us/pricing/details/app-service/