This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
20-year-male presents with fever, fatigue, posterior cervical lymphadenopathy, palatal petechiae, and splenomegaly. Peripheral smear shows atypical lymphocytes and the heterophile antibody is positive. The likely diagnosis is 
Select and explain. 
A. Acute leukemia, B. Lymphocytic leukemia, C. Infectious mononucleosis, D. Chronic myeloid leukemia
C: Infectious mononucleosis
Answer: C: Infectious mononucleosis 
Explanation: The Epstein-Barr virus is the cause of heterophil positive infectious mononucleosisFeatures are fever, sore throat, lymphadenopathy most often affects posterior cervical nodes but may be generalized, splenomegaly and atypical lymphocytosisIt is usually a disease of young adultsRef: Davidson's 20/e p307, Harrison; 18/e p1467-1468