Html.RadioButtonFor のcheckedの設定
@:Html.RadioButtonFor→ <label> @Html.RadioButtonFor(model => model.CheckRadioStr, "A", new { @checked = "checked" }) はい </label> <label> @Html.RadioButtonFor(model => model.CheckRadioStr, "B" ) いいえ </label>
html↓
<label> <input checked="checked" id="CheckRadioStr" name="CheckRadioStr" type="radio" value="A"> はい </label> <label> <input id="CheckRadioStr" name="CheckRadioStr" type="radio" value="B"> いいえ </label>