I have personally seen monospot test results mentioned on practice questions from AMBOSS and was supposed to lead us toward/away from choosing EBV. Clinical practice does not always line up with what we might see on Step. Original card is factually correct. AMBOSS specifically notes on their CMV infectious mononucleosis article that “Differential diagnosis: infectious mononucleosis caused by EBV (in the case of CMV, heterophile antibody test would be negative)” https://next.amboss.com/us/article/nf0752?q=monospot%20test%20cmv#Z43d7ca575a9668381a9551d052989509