Components in a Matching Drop-Down

Hello Storyline Community,

I'm building a quiz in which a bookmark is set if a learner skips a question to review it later.  I'm able to do that easily for multiple-response and choice questions by setting triggers to change the color (state) of the bookmark when the state of the radio buttons and check boxes remain normal instead of selected. However, I'm struggling to figure out components for a matching drop-down. All I see on the timeline is text boxes without any states. Please see the attached storyline file and the screenshot. 

I'm guessing I'm missing something simple and won't need to create a customized matching slide. Any pointers or guidance is appreciated.