Final answer:
Among the given symptoms of infectious mononucleosis, a rash is the exception and not typically a feature of the condition.
Step-by-step explanation:
Infectious mononucleosis, commonly known as glandular fever, is often characterized by several key symptoms: fever, sore throat, an enlarged spleen, and sometimes a rash; however, one of these is less commonly associated with the condition. Among the options given, rash is the EXCEPTION to the typical symptom display of infectious mononucleosis. While fever, sore throat, and an enlarged spleen are classic signs of the infection caused by the Epstein-Barr virus, a rash is not a common feature and is more typically associated with other viral infections, such as measles.