Final answer:
Antibiotic resistance in bacteria occurs due to natural selection, where resistant strains survive due to mutations and the overuse or incorrect use of antibiotics. This has become a major global health issue, as antibiotic resistance complicates the treatment of many infections.
Step-by-step explanation:
The phenomenon of antibiotic resistance in bacteria is best described by the statement indicating that the excessive use of antibiotics has resulted in the natural selection of resistant forms of bacteria. Mutations in bacteria that allow them to survive in the presence of antibiotic drugs lead to the development of resistant strains. This is largely due to the overuse and incorrect use of antibiotics, such as not completing a full course of prescribed antibiotics. When the antibiotic kills most of the infecting bacteria but not the resistant forms, these resistant forms survive and reproduce, thereby increasing the proportion of resistant bacteria over time.