how to make only one radio button selected code example

Example 1: how to add select only one radio button in html

<input type="radio" name="nameA" id="nameA" value="nameA">
<label for="nameA">Choice A</label>
<input type="radio" name="nameB" id="nameB" value="nameB">
<label for="nameB">Choice B</label>

Example 2: radio button css only 1

<input type="radio" name="radAnswer" /> 
<input type="radio" name="radAnswer" /> same name