What is the therapeutic classification of Metronidazole?

Metronidazole is classified as a nitroimidazole antibiotic, which is reflected in the choice that identifies it correctly. This classification is based on its mechanism of action and its chemical structure. Metronidazole works by disrupting DNA synthesis in susceptible bacteria and protozoa, making it effective against a variety of infections, particularly those caused by anaerobic bacteria and certain parasites such as Giardia and Trichomonas.

Other classifications like antifungal, antiviral, or corticosteroid do not align with metronidazole's specific use or action. Antifungals target fungal infections; antivirals are designed to combat viral infections; and corticosteroids are anti-inflammatory agents that modulate the immune response. None of these classifications apply to metronidazole's therapeutic properties, reinforcing that the correct answer is indeed the nitroimidazole antibiotic classification.