Before administering cefazolin (Ancef), the nurse checks for a previous allergic reaction to:

A. Yeast: Yeast allergies are unrelated to cefazolin or other beta-lactam antibiotics. B. Penicillins: Cefazolin is a cephalosporin antibiotic, and there is a potential for cross-reactivity with penicillins due to their similar beta-lactam ring structure. Checking for a penicillin allergy is essential before administering cefazolin. C. Macrolides: Macrolides have a different structure and do not cross-react with cephalosporins, so a history of macrolide allergy is not directly relevant. D. Sulfonamides: Sulfonamides have a different chemical structure, and there is no significant cross-reactivity with cephalosporins.