Correct Option: B

Penicillin is one of the earliest discovered and widely used antibiotic agents, derived from the Penicillium mold. Antibiotics are natural substances that are released by bacteria and fungi into their environment, as a means of inhibiting other organisms. In 1928, Sir Alexander Fleming observed that colonies of the bacterium Staphylococcus aureus could be destroyed by the mold Penicillium notatum, proving that there was an antibacterial agent there in principle. This principle later lead to medicines that could kill certain types of disease-causing bacteria inside the body.