You have a SharePoint Server 2010 server farm.

You plan to host multiple site collections in a single Web application.

You need to prevent user profiles from being shared between the site collections.

What should you do?

A.
Enable multi-tenant support.

B.
Create multiple profile databases.

C.
Create multiple content databases.

D.
Configure the Secure Store Service application.

Explanation:
BURGOS MNEMO: "multi-tenant"

Enabling Multi Tenant Support in SharePoint 2010
http://blogs.technet.com/b/speschka/archive/2009/11/30/enabling-multi-tenant-support-in-sharepoint-2010.aspx