Need help to select a div
===

I need to select by clicking  the 'C' from the dropdown and when I move over to the 'C' element.  its class gets change to "x-combo-list-item x-combo-selected".And when i use this code in code to click the  element it throws an exception 
 
"org.openqa.selenium.IllegalLocatorException: Compound class names are not supported. Consider searching for one class name and filtering the results."

drivefindElement(By.className("x-combo-list-item x-combo-selected")).click();
 
Could you please help me to get the way to click this element?
 
html code .. from Firebug
 
<--div id="xyz" class="x-combo-list-inner" style="width: 253px; height: 105px;">

  <--div class="x-combo-list-item" ext:qtip="">A<--/div>
  
<--div class="x-combo-list-item" ext:qtip="">B<--/div>
  
<--div class="x-combo-list-item x-combo-selected" ext:qtip="">C<--/div>
  
<--div class="x-combo-list-item" ext:qtip="">D<--/div>

<--div class="x-combo-list-item" ext:qtip="">E<--/div>

<--/div>
