Acondition that reduces the number of oxygen-carrying red blood cells is:

Anemia is a condition that reduces the number of oxygen-carrying red blood cells (rbcs). There are various types of anemia, ranging from lack of production of rbcs (hypoplastic), lack of sufficient iron in the oxygen-carrying proteins (hemoglobin) of rbcs (iron-deficiency), lack of cofactors needed to produce healthy rbcs (pernicious), and destruction of rbcs (hemolytic), to name a few of the more common forms of anemia.

A. vitamin c is your answer