Thinking of EMIs (also known as R-type MCQs) as matching one list of things with another is an over-simplification which may not be helpful in considering how to improve the UI.
In R-type MCQs, the options are thematically related to each other, and each item is almost like a separate question. Chapter 6 (pp. 71 - 97) in "Constructing Written Test Questions For the Basic and Clinical Sciences" from the NBME has an extensive description and examples:
Lastly, UCT commissioned the implementation of R-type MCQs (EMIs) in T&Q at the request of our Health Sciences Faculty, who use them extensively in online assessments. It would be helpful to hear from others who are using them, and actual experiences with students, to inform UI changes.