html select
<label for="cars">Choose a car:</label>
<select name="cars" id="cars">
<optgroup label="Swedish Cars">
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="n/a" disabled>unavailable</option>
</optgroup>
<optgroup label="German Cars">
<option value="mercedes" selected>Mercedes</option>
<option value="audi">Audi</option>
</optgroup>
</select>