哪个元素创建了一组选项?
<select name="number"> <option value="1">one</option> <option value="2">two</option> <option value="3">three</option> <option value="4">four</option> </select>
<!-- optgroup 标签定义选项组 --> <select> <optgroup label="间谍过家家"> <option value ="阿妮亚">阿妮亚</option> <option value ="黄昏">黄昏</option> <option value ="荆棘公主">荆棘公主</option> </optgroup> <optgroup label="地缚少年花子君"> <option value ="花子君">花子君</option> <option value ="八寻宁宁">八寻宁宁</option> <option value ="源光">源光</option> <option value ="三叶惣助">三叶惣助</option> <option value ="柚木司">柚木司</option> </optgroup> </select>