Pharmacology Although tetracycline is a broad-spectrum antibiotic but resistance to the drug developed by the following mechanism: A By inactivating enzymes. B An efflux pump mechanism. C Alteration of the binding site. D Absence of a metabolic pathway. 💡 Explanation Although tetracycline is a broad-spectrum antibiotic but resistance to the drug developed by the following mechanism: ✓ Correct Answer: B. An efflux pump mechanism.