Drop down menu open by default php

I have this script for a drop down box which is closed until the user clicks the down arrow, showing the options. I want it so all the options are displayed from the start, so they don't have to select the down arrow. Does anyone know what i need to change in order to achieve this? (I think it has something to do with the 'explode' function?)

<?php
                              $options = explode(',', $values);
                              $optionCursor = 1;
                              $checked = '';
                              ?>