Unlike red blood cells, white blood cells
a. can live for many years.
b. carry oxygen through the body.
c. are the most numerous cells in the blood.
d. are made in the bone marrow.

The answer is neither of the above. All the above features except A relate to the red blood cells. (A is not true for both red blood cells and white blood cells.) Red blood cells or RBCs carry oxygen, are the most numerous cells (36 - 50%) in the blood and they are made in the bone marrow. The life span of RBCs is 120 days or 4 months. On the other hand, white blood cells or WBCs produce antibodies to develop immunity against infections and some are phagocytic against pathogens. They make up about 1% of the blood and are produced in the thymus. The lifespan of WBCs is 4 - 30 days.