Final answer:
Clients saving remaining antibiotics for the next time they feel sick has contributed to the problem of resistant bacteria.
Step-by-step explanation:
The practice that has contributed to the problem of resistant bacteria is clients saving remaining antibiotics for the next time they feel sick. This practice leads to incomplete or incorrect treatment of bacterial infections and allows the surviving bacteria to develop resistance to the antibiotic. When antibiotics are not taken as prescribed, some bacteria can survive and pass on their resistance to future generations.