I believe it is "Secondary"
Honestly I wouldnt take my advice because I know nothing really about this but I believe its either B or D. But I'm more lenient on D because the patient could be having a allergic reaction to the medicine so that it may not have developed into Aids just yet. but I also said B because it may be a likely chance that it has evolved into Aids BUT I have no idea what a CD4+ count is so sorry if I wasn't much help lol
The answer is Mitosis.
The zygote divides through a process called mitosis, in which each cell doubles by dividing into two cells.