conditions and variables question

I am new to this and I'm sure this can be done but I'm not sure how. 

I have a branching scenario. I want the user to get to the correct answer for each of the three scenarios. And when that has occurred, he/she will hit the home button but the branch selection side with show a "Great Job" and attribution layer. 

I know I can create a true/false variable. And I guess I'm thinking I should have something on each of my 3 correct answer slides. But what? Adjust variable trigger when slide starts to change visited to true??

I'm going to try that but if there is a better way, please let me know.

Thanks in advance.