Question

which of the following is responsible for making blood red?
the antibodies from the white blood cells
the iron in oxygenated blood
the iron in deoxygenated blood

Explanation:

Antibodies from white blood cells are for immune response, not color. Deoxygenated blood's iron - containing hemoglobin (deoxyhemoglobin) has a darker red/purple hue. Oxygenated blood has oxyhemoglobin, and the iron in it (as part of oxyhemoglobin) gives blood its bright red color.

Answer:

the iron in oxygenated blood