Answer:
A
Step-by-step explanation:
All living organisms pass on or transfer their genetic material to their offsprings. However, this transfer of genes occurs through the process of reproduction (sexual or asexual). Reproduction may (in case of sexual) or may not (in case of asexual) ensure genetic variation among species.
Eukaryotes that undergo sexual reproduction increase genetic variation among their species by undergoing Crossing-over (exchange of chromosomal segment between non-sister chromatids of homologous chromosomes) during meiosis or gamete formation. This process of transferring genetic material directly from parents to offsprings is called VERTICAL GENE TRANSFER, and only sexual-reproducing eukaryotes ensure genetic variation through this process.
On the other hand, prokaryotic organisms cannot undergo sexual reproduction, they undergo asexual reproduction instead and asexual reproduction does not guarantee genetic variation since identical daughter cells as the parents are produced from the process. However, to promote genetic variation among their species, they employ the processes of transformation, transduction and conjugation which are all forms of HORIZONTAL GENE TRANSFER because it involves transfer of genetic material from one cell (donor) to another (recipient) which do not have the parent-offspring relationship.