Tetracycline and penicillins are:

Explanation

Option A: Disinfectants are chemicals that kill microorganisms on surfaces. They are used to clean and sanitize surfaces in hospitals, clinics, and other healthcare settings. Option B: Tetracycline and penicillins are antibiotics. Antibiotics are medications that kill or inhibit the growth of bacteria. They are used to treat bacterial infections, such as strep throat, pneumonia, and urinary tract infections. Option C: Antiseptics are chemicals that kill or inhibit the growth of microorganisms in living tissue. They are used to clean and disinfect wounds and other breaks in the skin. Option D: Antigens are substances that the body's immune system recognizes as foreign. They can trigger an immune response, which can lead to the production of antibodies.