MAYBE it wasn't a differentiator then! The one we had was stupid...my friend works in the lab with the coordinator and she asked him to tell her what the right answer was and he was like 'I'm not going to tell you because we use it every year but if too many people get it wrong we don't include it in the final grades'.
I just got really confused by the question because we have different lecturers for every topic and every other question this guy had asked was shit like 'what is the role of CD8 cells, a. to kill infected host cells' etc. so I was like nah he wouldn't be trying to trick us MUST BE a wrong question. IMMUNOLOGY. It was multiple completion too, don't do subjects with multiple completion.