Answer:
The correct answer is b. horizontal gene transfer
Step-by-step explanation:
Horizontal gene transfer is the process by which a bacterial species can acquire the antibiotic-resistant gene from another bacteria that already have that gene.
Horizontal gene transfer can be carried out by three mechanisms that are conjugation, transformation, and transduction. In conjugation one bacteria takes the genetic material of another bacteria through sex pillus.
In tranformation a bacteria takes up a genectic material from its surrounding and in transduction bacteriophage mediate the transfer of genetic material in the bacteria through infection.
Therefore the right answer is b. horizontal gene transfer