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: Pharmacology
A patient's history notes a documented severe reaction to a penicillin. What other antibiotic is likely to cross-react and so should be avoided in this patient? 
Select and explain. 
A. Aininoglycosides, B. Azithromycin, C. Cephalosporins, D. Erythromycin
C: Cephalosporins
Answer: C: Cephalosporins 
Explanation: Unless there are no reasonable alternatives, cephalosporins should be avoided for patients with prior severe responses to penicillins because of their cross- reactivity. None of the other drugs or drug groups listed here cross-react in penicillin-sensitive patients.