A radio button allow user to select single value for submission in a form.
array(
'id' => 'radio_1',
'type' => 'radio',
'title' => 'Radio Fancy',
'options' => array(
'yes' => 'Yes, Please.',
'no' => 'No, Thank you.',
),
'default' => 'no', // optional
'style' => 'fancy', // optional
),