You create a Feature.
You need to add an item to the context menu of a list.
Which type of element should you use?
A.
a CustomAction
B.
a ListInstance
C.
a ListTemplate
D.
a Module
Explanation:
MNEMONIC RULE: “context menu item = CustomAction”A custom action can be added inside a secondary XML file, part of a normal feature. It is defined by a “CustomAction” element type.
How to add a custom action to list elements context menu
http://www.dev4side.com/community/technical-articles/sharepoint-2007/how-to-add-a-custom-action-to-list-elements-context-menu.aspx