Which assembly defines the non-core messages and enumerations needed for working with organization data?

You use the Microsoft Dynamics CRM SDK to build plug-in code in Microsoft Visual Studio.
Which assembly defines the non-core messages and enumerations needed for working with
organization data?

A.
Microsoft.Xrm.Sdk.Deployment.dll

B.
MicrosoftCrm.SdkProxy.dll

C.
MicrosoftXrm.Sdk.dll

D.
Microsoft.Xrm.Sdk.Workflow.dll