This is my code

$form['option_city'] = array( '#type' => 'radios', '#title' => t('City'), '#description' => t('Reservation'), '#options' => array( t('City'), t('Address'), ), '#default_value' => variable_get('option_city', 0) // default to Never );

When i select " City " Display the Cityform

When i select " Address " Display the AddressForm

How to write the code for this situation