Built-in/System Variables & Element States

Yes indeed you can do this. From the drop down of variables you can only select the Custom variables. However you are wanting to trigger this off a system variable. Here is the most common methods to accomplish this: 

1. Set the trigger to be when the page loads (timeline / page timing) trigger.
2. Under the last step where you see the blank conditions box, this is where you add in the conditions.
   1. Right click or type {{ to get the list of variables and select the pretest score for the current module variable add your argument and then score.
      1. e.g., 

         {{sys.currentModule.pretest}} == 90

         or
          

         {{sys.currentModule.pretest}} > 80

The end result is your state will look to change on page load, but only if it ALSO meets the specific condition.