You are developing an application that performs file backups in the background. The background application
will host a Windows Communication Foundation (WCF) service and must be active as soon as the machine is running.
The background application will not have a user interface. A front-end application will consume the WCF service and will provide the user interface.

You need to choose a host environment for the WCF service. Which hosting environment should you choose?

A.
Microsoft Internet Information Services (IIS) 6.0

B.
Windows Process Activation Services (WAS)

C.
A Windows Forms application

D.
A Windows Service

Explanation:
Hosting Services
(http://msdn.microsoft.com/en-us/library/ms730158.aspx)

Hosting Options:
1. Self-Hosting in a Managed Application (self-hosted)
2. Managed Windows Services
3. Internet Information Services (IIS)
4. Windows Process Activation Service (WAS)