Answer:
Option A. specialized transduction and Option D. acquisition of an F' factor.
Step-by-step explanation:
A partial diploid strain occurs in a bacteria due to specialized transduction and the acquisition of an F' factor.
This allows the bacteria to have or possess duplicates (2 copies) of some of its genetic elements (Chromosomes). One of those copies can be found on the chromosome of the bacteria while the second copy can be found in the plasmid of the bacteria.
Bacteria that have been found to possess the partial diploid strain are known as Merodiploids.