Angular/ngSelected

    
<label><input type="checkbox" ng-model="selected"></label>
<select>
  <optgroup label="aaa">
  	<option>aaa</option>
  	<option>bbb</option>
  </optgroup>
  <optgroup label="ccc">
  	<option ng-selected="selected">ccc</option>
  	<option>ddd</option>
  </optgroup>
</select>