heather this is awesome, thank you for sharing this and big THANK YOU for the screenr, i always love to see the visual of how people put something together!!!
one thing that might also be helpful for future projects: I recently found out that Storyline has 2 built-in states that are great for drag and drop interactions... DROP CORRECT and DROP INCORRECT. I just wanted to mention this because if you were to use those instead of making the 2 custom states for the correct/incorrect colors on each drag item, you wouldn't need the triggers at all. Because Storyline will apply the state for you as soon as the user drops the item. This could save a little bit of work . because it means you wouldn't have to add the 2 triggers for each of your items.
thank you again for sharing!