Buy One <input type="radio" name="yesno" id="one">

Buy Two <input type="radio" name="yesno" id="two">

Buy Three <input type="radio" name="yesno" id="three">

Buy Four <input type="radio" name="yesno" id="three">

  <br>
<select id="first">
  <option value="chevy">Chevy</option>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
</select>
   <br>
<select id="second">
  <option value="chevy">Chevy</option>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
</select>
   <br>
<select id="third">
  <option value="chevy">Chevy</option>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
</select>
  <br>
<select id="fourth">
  <option value="chevy">Chevy</option>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
</select>

.visible { display: block; }
.hidden { display: none;}

function hideSelector (){
    var seltwo = document.getElementById("second");

    seltwo.addClass("hidden");
};

document.getElementById("one").addEventListener("click", hideSelector);