How should the consultant determine if all regions are using Salesforce?

Cloud Kicks just deployed SalesCloud globally and wants to make sure that all of its users are using Salesforce.

How should the consultant determine if all regions are using Salesforce?
A . Assign all users to a region, build a report using user login history, and filter on region.
B . Create an Opportunity report per region, filtering by User.
C . Ask each regional sales manager to run the standard User Adoption report.
D . Install Salesforce Adoption Dashboards from the AppExchange and use the region chart.

Answer: D