Returns HTML for a select form element.
It is possible to group options together; to do this, change the format of $options to an associative array in which the keys are group labels, and the values are associative arrays in the normal $options format.
$variables: An associative array containing:
function theme_select($variables) {
$element = $variables['element'];
element_set_attributes($element, array(
'id',
'name',
'size',
));
_form_set_class($element, array(
'form-select',
));
return '<select' . drupal_attributes($element['#attributes']) . '>' . form_select_options($element) . '</select>';
}