Conditional Dropdown Choices on Ticket Form

We are setting up a new LMS, and want FS to handle tickets for our existing software products and also the LMS. The problem is that users can have issues with the LMS that simply don’t apply to other products (course doesn’t complete, didn’t get my certification, etc). It’s confusing for users to select “Word” for “System affected” and then see “Course didn’t complete” as an option in the “Specific Issue” drop-down. A drop-down menu whose items populated depending on the choice made in a prior drop-down menu would solve this problem. Right now, we either have to live with the confusion or create two different ticket forms.