You have a SharePoint Server 2010 server farm.

You have a SharePoint solution named Solution1. Solution1 contains a feature named Feature1. Featue1 installs a custom Web Part to the Global Assembly Cache.

You deactivate Feature1 and retract Solution1 from the server farm.

The custom Web Part still appears on the list of Web Parts that users can add to Web Part pages.

You need to prevent the custom Web Part from appearing on the list of Web Parts that users can add to Web Part pages.

What should you do?

A.
Modify the default.master master page.

B.
Run gacutil.exe and specify the uninstall parameter.

C.
Run stsadm.exe and specify the deletesolution operation.

D.
Delete the Web Part descriptor from the Web Part Gallery.

Explanation:
BURGOS MNEMO: "Web Part descriptor"