Variables with question level triggers

I have a quiz that contains questions of three difficulty levels.  Here is what I want to do:

1:  show total result that includes scores of all the questions

2:  show total questions correct per each difficulty level

So basically the results slide will show four things

1:  Total score

2:  # of difficulty level 1 correct

3:  # of difficulty level 2 correct

4:  # of difficulty level 3 correct

Also, I would want to know if this quiz hosted on Articulate Online can show the report all the four scores so that I can run stats on the class that takes this quiz.

One solution that I thought of was creating variables for each difficulty level and incrementing the variables as the student correctly answers the question in that difficulty level correct.  But I do not know the trigger that I would use for the adjustment of that variable.  Is there is a question level trigger that says that this question is correct or incorrect?

I look forward to your response.

Regards,

Payal