A reduction in the blood's ability to carry oxygen due to a lack of red blood cells or haemoglobin is called what?

• A. Leukaemia
• B. Polycythemia
• C. Thrombocytopenia
• D. Anaemia

Answer: (D)

The key idea is how oxygen is carried in the blood. Oxygen is transported by red blood cells that contain haemoglobin; when there aren’t enough red blood cells or the haemoglobin level is low, the blood can’t carry as much oxygen as it should, which is known as anaemia. Leukaemia is a cancer involving white blood cells, which can disrupt blood cell production but is not defined by a reduced oxygen-carrying capacity. Polycythemia is the opposite situation—too many red blood cells—leading to thicker blood rather than impaired oxygen transport. Thrombocytopenia means a low platelet count, affecting clotting, not oxygen delivery. So the description fits anaemia, the condition of reduced oxygen-carrying capability of the blood.