Which of the following anti-infectives is a fluoroquinolone?

A. Ciprofloxacin is a fluoroquinolone antibiotic that is effective against a broad spectrum of bacteria and is commonly used to treat various infections. B. Cephalexin is a cephalosporin, not a fluoroquinolone. C. Penicillin is a beta-lactam antibiotic, distinct from the fluoroquinolone class. D. Azithromycin is a macrolide antibiotic and does not belong to the fluoroquinolone class.