Radio Button

<fieldset class="usa-fieldset-inputs usa-sans">

    <legend>Historical figures 2</legend>

    <ul class="usa-unstyled-list">
        <li>
            <input id="stanton" type="radio" checked name="historical-figures-2" value="stanton">
            <label for="stanton">Elizabeth Cady Stanton</label>
        </li>
        <li>
            <input id="anthony" type="radio" name="historical-figures-2" value="anthony">
            <label for="anthony">Susan B. Anthony</label>
        </li>
        <li>
            <input id="tubman" type="radio" name="historical-figures-2" value="tubman">
            <label for="tubman">Harriet Tubman</label>
        </li>
    </ul>

</fieldset>

<!-- Validation - Error -->
<fieldset class="usa-fieldset-inputs usa-input-error">

    <legend>Historical figures 2</legend>
    <span class="usa-input-error-message" id="input-error-message" role="alert">Helpful error message</span>

    <ul class="usa-unstyled-list">
        <li>
            <input id="stanton" type="radio" checked name="historical-figures-2-error" value="stanton">
            <label for="stanton">Elizabeth Cady Stanton</label>
        </li>
        <li>
            <input id="anthony" type="radio" name="historical-figures-2-error" value="anthony">
            <label for="anthony">Susan B. Anthony</label>
        </li>
        <li>
            <input id="tubman" type="radio" name="historical-figures-2-error" value="tubman">
            <label for="tubman">Harriet Tubman</label>
        </li>
    </ul>
</fieldset>