You need to reduce the storage costs associated with the VMs

You manage an Azure subscription with virtual machines (VMs) that are running in Standard mode.
You need to reduce the storage costs associated with the VMs.
What should you do?

A.
Locate and remove orphaned disks.

B.
Add the VMs to an affinity group.

C.
Change VMs to the Basic tier.

D.
Delete the VHD container.

Explanation:
Standard offers 50 GB of storage space, while Basic only gives 10 GB but it will save costs.
http://azure.microsoft.com/en-us/pricing/details/websites/