Answer:
C. antigen-antibody reactions
Explanation:
human blood group is determined by the presence of antigens on the red blood cells which are specific proteins.
so specific antibodies are used against these antigens to determine the type of blood group after the reaction.
Carries oxygen from pulmonary alveoles to tissue and returns carbon dioxide from tissue to the lungs. and has Fe ions that gives blood the specific red color. and veins specific purple red color is given after oxygen is realesed to the tissue by oxihemoglobine ( at low ph and high temperature because at those conditions the hemoglobine capacity of bonding dicreases) .
The answer is C, the mitochondria is the powerhouse of the cell
