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.
Answer is B. Tetracyclines are broad-spectrum bacteriostatic drugs. Development of resistance to  tetracyclines are mainly due to the development of efflux pumps.