无法一次选择一个单选按钮

我无法一次选择一个单选按钮。多个按钮被选中。我是 html 新手。这是我的代码。请帮忙。

<form name="ans_a" onsubmit="return answer_a()">
    <table align="center" border="1">
        <br>
        <br>
        <tr>
            <td width="500px"> ABC 
                <br>
                <input type="radio" name="A" value="a" id="radio1"> A &nbsp Option A <br>
                <input type="radio" name="B" value="b" id="radio2"> B &nbsp Option B <br>
                <input type="radio" name="C" value="c" id="radio3"> C &nbsp Option C <br>
                <input type="radio" name="D" value="d" id="radio4"> D &nbsp Option D <br>
                <br>
                &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp
                <input type="button" name="ans1" value="Next" onclick="answer_a()">
            </td>
        </tr>
    </table>
</form>

名称属性必须相同才能仅选择一个无线电button一次。 ID 可能会有所不同，具体取决于您是否想要在选择单选按钮之一的地方捕获该 ID。

<input type="radio" name="A" value="a" id="radio1"> A &nbsp Option A <br>
<input type="radio" name="A" value="b" id="radio2"> B &nbsp Option B <br>
<input type="radio" name="A" value="c" id="radio3"> C &nbsp Option C <br>
<input type="radio" name="A" value="d" id="radio4"> D &nbsp Option D <br>