Showing List of category inside category?

hello, i would like to ask..
is there a way to show all category inside a category?

category
A
-B
-C
-D
-E

A2
-F
-G
-H
-I

i want to show ALL category inside category A and A2 [show all level 2 category]
how?

Hi,
The best solution will probably be to set the "sub element filter" to All sub elements through your category listing content menu/module configuration page.