The company is implementing XenDesktop globally for desktop virtualization.
Why should an architect recommend multiple controllers in each datacenter?

A.
To protect against controller database failure

B.
To enable users to maintain uninterrupted connection to their desktops

C.
To protect users from WAN link failure

D.
To ensure that new desktop and application sessions can be launched

Explanation:
http://support.citrix.com/servlet/KbServlet/download/33432-102- 705920/StoreFront%20Planning%20Guide.pdf(page 10, delivery controllers)