Answer:
b
Step-by-step explanation:
The correct answer would be that patients are not taking the antibiotic for the length of time prescribed and so selection for resistant bacteria that can survive a limited course of antibiotic is occurring.
When the concentration of the antibiotic in the blood is not up to the minimum bactericidal concentration as a result of inadequate dosage, natural selection acts on the bacterial population and those with the antibiotic-resistant gene are selected over those without the resistant gene.
Consequently, the surviving bacteria with the resistant gene regroup, multiply and become dominant in the population than ever before. Subsequent use of the same antibiotic by patients will be met with the antibiotic-resistant gene and renders the antibiotic ineffective in the treatment of the disease caused by the bacterial pathogen.
The correct option is b.