Concept:The ABO blood group system is based on antigens on red blood cells and antibodies in plasma.
Explanation:Antigens are protein markers present on the surface of red blood cells.
Antibodies are defensive proteins found in the blood plasma, not on cells.
Option A is wrong because antigens are not on white blood cells.
Option C is wrong because antibodies are not on red blood cells.
Option D is wrong because antigens are not in plasma.
Therefore, the correct statement is that antibodies are located in the blood plasma.
Answer:B. Antibodies are located in the blood plasma.