Selection screen urgent

Hi .

Would  you please help me about define a selection with this rules ..On selection screen  select-options date for sy-datum .

if radio button A selected I want to refresh date's screen only year and this selection will be in terms of whole year .

if radio button B selected I want to refresh date's screen only month and year (01.2006 - 04-2006 ) .and make this selection available 01.01.2006 - 31.04.2006.User do not have to see days .

if radio button C selected I want to refres date's screen as listbox 1.period 2. period 3. period . And 1 . period is selected make available 01.01.2006 .31.04.2006.

2.is selected  01.05.2006. 31.08.2006.

3. is selected 01.09.2006 31.12.2006.

Thanks in advance ..