Ans. (B). ' Since iron is required to make hemoglobin and myoglobin, iron deficiency decreases the amount of oxygen in the blood and in the muscles.'
Anemia represents deficiency of blood cells to deliver sufficient oxygen throughout the body organs. Myoglobin and hemoglobin are oxygen-transporting proteins, present in muscles and red blood cells, respectively.
Both these proteins are made up of polypeptide chains and heme groups. The heme group contains iron, hence, iron-deficiency causes insufficient amount of myoglobin and hemoglobin. Due to this, the amount of oxygen decreases in muscles and blood and leads to anemia.
Thus, the correct answer is option (B).