how to display different items for different users?

There is a drop-down-list on the page; What i want here is to display different items for different situations.

such as: for you check "check-box A", item A, B, C can be displayed; and checking "check-box B", item C, D, E should be displayed...

is there any way to make it?

BTW, I use C#, and VB....

thanks,
Jessie