This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
A previously healthy eight year old boy presented to the emergency depament with high grade fever, ahralgia, pruiritic erythematous rash and lymphadenopathy. He has completed 8 days out of a 10 day course of cefaclor for an upper respiratory tract infection. Which of the following is the most likely diagnosis? 
Select and explain. 
A. Kawasaki Disease, B. Type III Hypersensitivity Reaction, C. Serum sickness Like Illness (SSLI), D. Henoch schonlein purpura
C: Serum sickness Like Illness (SSLI)
Answer: C: Serum sickness Like Illness (SSLI) 
Explanation: Boy in the questions who developed the fever,rash,lymphadenopathy, after taking cefaclor for UI is suffering from drug induced serum sickness. Ref: Essentials of emergency medicine By Richard Aghababian page307; What to do About Allergies By Harvard Health Publications page 8.