You need to ensure that users can refine their document searches based on the content type of the document

You are the administrator for a SharePoint 2010 farm that contains a document library that has multiple content types.

No additional metadata is gathered when documents are uploaded.

You need to ensure that users can refine their document searches based on the content type of the document.

What should you do? (Choose the best answer.)

A.
Create a secure store application for the document types and a managed property that references the secure store. Add the new application to the search refinement panel definition.

B.
Create a new list that includes a column to store the document type. Add a lookup to this list in the document content type. Crawl the property, create a managed property and mapping, and add the property to the search refinement panel definition

C.
Create a choice column in the document content type. Crawl the property, create a managed property and mapping, and add the property to the search refinement panel definition.

D.
Create a managed metadata term set for document types and include the managed metadata in the document content type. Add the new column to the search refinement panel definition.