You create Microsoft Windows-based client applications. You are designing a smart client application for warehouse packaging clerks. The application must permit the clerks to add and delete items in the packaging invoices they create at their workstations. Each workstation has only a keyboard and a hand-held barcode scanner for input. You need to design the user interface for the application such that the clerks can add and delete items with minimum effort. What should you do?

A.
Add to the form a context menu that has Add to Invoice and Remove from Invoice menu items.

B.
Add to the form a menu that has Add to Invoice and Remove from Invoice menu items.

C.
Add to the form a KeyPress event handler that toggles between Add to Invoice and Remove from Invoice modes.

D.
Add to the form a ToolStrip control that has a button that toggles between Add to Invoice and Remove from Invoice modes.