You use Microsoft .NET Framework 4.0 to develop an application that exposes a WCF Data Services endpoint.
The endpoint uses an authentication scheme that requires an HTTP request that has the following header format.

GET /OData.svc/Products(1)
Authorization: WRAP access_token “123456789”

You add the following method to your DataService implementation.

01 protected override void OnStartProcessingRequest(ProcessRequestArgs args)
02 {
03 ….
04 }

You need to ensure that the method retrieves the authentication token. Which line of code should you use?

A.
string token = args.OperationContext.RequestHeaders[“Authorization”];

B.
string token = args.OperationContext.RequestHeaders[“WRAP access_token”];

C.
string token = args.OperationContext.ResponseHeaders[“Authorization”];

D.
string token = args.OperationContext.ResponseHeaders[“WRAP access_token”];

Explanation:
OData and Authentication OAuth WRAP
(http://blogs.msdn.com/b/astoriateam/archive/2010/08/19/odata-and-authentication-part-8-oauth-wrap.aspx)