Answer:
The correct answer is- bacterial infection.
Step-by-step explanation:
Antibiotics are the antibacterial drugs that are used to kill bacteria or slow down its growth. The first antibiotic was discovered by Alexander Fleming in 1928 and that antibiotic was penicillin.
Now many antibiotics are present in the market which are used to treat bacterial infection in humans and animals. Antibiotics have many targets in bacteria to kill it or inhibit its growth.
Penicillin works on the cell wall of gram-positive bacteria and does not allow the formation of new peptidoglycan layer in bacteria which results in the lysis of bacterial cell. As animal cells do not contain cell wall it does not harm the animal cell.