A) This statement is incorrect because anemia is characterized by a decrease in red blood cell production or an abnormal decrease in hemoglobin levels, not an increase in red blood cell production.

B) This statement is incorrect because anemia is caused by a deficiency in iron, not an excess of iron.

C) This statement is correct. Anemia is characterized by a reduced number of red blood cells or a decreased hemoglobin concentration, which leads to a diminished ability of the blood to carry oxygen throughout the body.

D) This statement is incorrect. Anemia is not caused by a viral infection affecting the bone marrow; rather, it is typically caused by nutritional deficiencies, chronic diseases, or blood loss.