Final answer:
Mechanism of acquired antimicrobial drug resistance: mutation, conjugation, transformation, and vertical gene transfer.
Step-by-step explanation:
The correct answer is d. Vertical gene transfer. Vertical gene transfer refers to the transfer of genes from parent to offspring, while mechanisms such as mutation, conjugation, and transformation are examples of horizontal gene transfer.
Horizontal gene transfer is the transfer of genetic material from one organism to another that is not its offspring. In the context of acquired antimicrobial drug resistance, mechanisms such as mutation, conjugation, and transformation play a significant role in spreading resistance genes among bacterial populations.