Which one of the following antimicrobial drugs is suitable for treatment of both tuberculosis and leprosy?

1. The question asks for an antimicrobial drug suitable for treating both tuberculosis (TB) and leprosy. 2. Both tuberculosis and leprosy are chronic infectious diseases caused by bacteria belonging to the genus Mycobacterium (Mycobacterium tuberculosis for TB, Mycobacterium leprae for leprosy). 3. Rifampicin (also known as Rifampin) is a powerful, broad-spectrum antibiotic that is highly effective against mycobacteria. 4. It is a cornerstone drug in the multi-drug therapy regimens recommended for both tuberculosis and leprosy. 5. Other drugs listed have more specific uses: Isoniazid and p-aminosalicylic acid (PAS) are primarily anti-TB drugs. Streptomycin is used for TB but less commonly for leprosy compared to Rifampicin.