使用Prototype JS更改选择选项

I have several dropdowns:

我有几个下拉菜单:

<select class="drop">
    <option value="1">Value 1</option>
    <option value="2">Value 2</option>
</select>

<select class="drop">
    <option value="1">Value 1</option>
    <option value="2">Value 2</option>
</select>
<select