Which class should you use?

You create a Web Part. The Web Part requires configuration information from the user. You plan to provide a custom interface for a custom field.

You need to derive a class to implement the custom interface.

Which class should you use?

A.
Microsoft.SharePoint.WebPartPages.WebPart

B.
Microsoft.SharePoint.WebPartPages.ToolPart

C.
Microsoft.SharePoint.Administration.SPWebConfigModification

D.
System.Web.UI.WebControls.WebParts.WebPart