Suppose a Doctor Prescribes a 10-Day Course of Antibiotics for a Child

Suppose a doctor prescribes a 10-day course of antibiotics for a child with an ear infection. The child is better in three days so the parent stops giving the child the medicine. A month later the child complains of ear pain again. The doctor prescribes the same medication but it does not work. The doctor then prescribes a stronger medicine. What process does this best illustrate?

A) Phenotype variation of the bacteria causing the ear infection
B) Biological evolution of the antibiotic
C) Speciation of the population of bacteria causing the ear infection
D) Biological evolution of the bacteria causing the ear infection
E) Genetic drift of the antibiotic