Answer:
A. destruction of the beta-lactam ring of the penicillin
Step-by-step explanation:
Penicillins and other antibiotics in the beta-lactan family usually contain a characteristic four-membered ring of beta-lactam.
A penicillin is capable of killing bacteria by binding β-lactam to DD-transpeptidase (a bacterial enzyme that binds peptidoglycan chains to form rigid moving cell walls), inhibiting its activity and preventing the formation of a new cell wall.
Without a cell wall, bacterial cells become vulnerable to external water and molecular pressures, and thus die quickly.
Bacteria can generate resistance to penicillin by producing beta-lactamase, a bacterial enzyme that destroys the penicillin beta-lactan ring, rendering it ineffective.
An example of penicillin-resistant bacteria is Staphylococcus aureus, which produces high amounts of β-lactamase. This bacterium can cause skin, blood or lung infections.