xxxxxxxxxx<html><head><meta charset="utf-8"> <title>W3Cschool(w3cschool.cn)</title> </head><body><select> <optgroup label="Swedish Cars"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> </optgroup> <optgroup label="German Cars"> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </optgroup></select> </body></html>