selection screen

hello,

I have three blocks in my selection screen.

in the first block i have one select-option

and in the second and third blocks i have 2 , 6 radio buttons respectively

depending on the select-option i give in block one,block 2 or block 3 any one of them has to get displayed.

if block 2 is active then block 3 should not get displayed and vice versa.

Plz let me know if any one have idea on this.

Thanks

Kumar