title: Change dropdown options if radio button selected
body: <p>I have 3 radio buttons selected, if the user chooses one of them I am wanting all but 2 options to disappear from a dropdown list further down the page, can anyone help please? If someone selects the third option (id="notify_type3") then I only want the dropdown to show an initial "select" (<code>&lt;option value=""&gt;Please select&lt;/option&gt;</code>) and one other option (for example, <code>&lt;option value="4"&gt;Option 4&lt;/option&gt;</code>), if the other 2 radio buttons are selected then it needs to show the whole list.</p>
  
  <pre><code>Staff member
  &lt;input type="radio" name="notify_type" id="notify_type1" value="new member of staff"&gt;
  Editorial Freelance
  &lt;input type="radio" name="notify_type" id="notify_type2" value="new freelance user"&gt;
  Contractor/Consultant
  &lt;input type="radio" name="notify_type" id="notify_type3" value="new contractor user"&gt;
  
  &lt;select class="dropdown" name="starter_company" id="starter_company"&gt;
  &lt;option value=""&gt;Please select&lt;/option&gt;
  &lt;option value="1"&gt;Option 1&lt;/option&gt;
  &lt;option value="2"&gt;Option 2&lt;/option&gt;
  &lt;option value="3"&gt;Option 3&lt;/option&gt;
  &lt;option value="4"&gt;Option 4&lt;/option&gt;
  &lt;option value="5"&gt;Option 5&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>