Question

lo 2.2. what determines a persons blood type?
presence or absence of certain proteins on the surface of red blood cells
blood type is determined by the color of the blood
blood type is determined by the presence of certain proteins in the plasma
the amount of iron in a persons blood
blood type is determined by the size of the red blood cells

Explanation:

Blood types (like A, B, AB, O) are determined by the presence or absence of specific antigens (which are proteins) on the surface of red blood cells. For example, type A has A antigens, type B has B antigens, AB has both, and O has neither. The color of blood (due to hemoglobin) is not related to blood type. Proteins in plasma (like antibodies) react with antigens but don't determine the blood - type itself. Iron amount affects things like oxygen - carrying capacity (related to anemia, for example) but not blood type. The size of red blood cells is relevant in conditions like microcytic or macrocytic anemia, not blood typing.

Answer:

Presence or absence of certain proteins on the surface of red blood cells