Why would you want to create a control block in a Forms module?

A.
To control all items in other blocks that are not base table items.

B.
To control relationship between a master block and its detail block.

C.
To control the way additional forms are opened and to track the call stack.

D.
To control navigation within the form so that users cannot randomly navigate to any item.

E.
To place various control items (such as buttons) on a single block that is not related to a table in the database.