How can you modify a text item so that only numeric keystrokes are accepted in the item at run time?

How can you modify a text item so that only numeric keystrokes are accepted in the item at run time?

A.
This cannot be accomplished.

B.
Set a numeric format mask to that text item.

C.
Create a bean area in place of the text item.

D.
Create a When-Validate-Item trigger on the text item.

E.
Set the implementation class property of the item to a pluggable Java component class.