The correct option is C monkey
Rh factor is a protein called an antigen that is found on the red blood cells of most people. If your blood has the protein, you're Rh positive. If your blood lacks the protein, you're Rh negative.
Rh factor is named after the Rhesus monkey. Experiments by Karl Landsteiner and Alexander S. Wiener, showed that rabbits, when immunized with rhesus monkey red cells, produce an antibody that also agglutinates the red blood cells of many humans.