Which condition is defined by a reduction in the number of red blood cells in the circulating blood volume?

• A. Sickle Cell Anemia
• B. Anemia
• C. Hemophilia
• D. Renal Calculi

Answer: (B)

A decrease in the circulating red blood cell mass means there are fewer cells to carry oxygen to the tissues, which is the defining feature of anemia. That makes anemia the best answer because the question is describing a reduced red blood cell count as the core characteristic. Sickle cell anemia is a form of anemia caused by abnormal hemoglobin that can lead to sickling and hemolysis, but the definition given points to a general reduction in red blood cells, not the specific sickle shape or mechanism. Hemophilia is a bleeding disorder due to clotting factor deficiencies, not related to red blood cell numbers. Renal calculi are kidney stones and have no direct connection to red blood cell counts. In short, anemia is the condition characterized by fewer red blood cells, limiting oxygen delivery to the body's tissues.