What condition can reduce the amount of oxygen carried in the blood?

Anemia is a condition that directly affects the blood's capacity to carry oxygen. In anemia, there is a deficiency in the number of red blood cells or hemoglobin, a protein within red blood cells that binds to oxygen. When there are fewer red blood cells or when the hemoglobin is not functioning properly, the total amount of oxygen that can be transported to the body's tissues is reduced. This can lead to symptoms such as fatigue, weakness, and shortness of breath, as the body struggles to meet its oxygen needs.

In contrast, other options like hemophilia primarily affect blood clotting and do not directly impact oxygen transport. Hypoxia refers to a state in which there is insufficient oxygen available, but it is more a consequence of various conditions rather than a specific blood condition that reduces oxygen-carrying capacity. Hyperventilation leads to an excess of oxygen in the blood and does not decrease oxygen levels; instead, it can result in altered blood chemistry. Thus, anemia is the most direct condition that reduces the oxygen carrying capacity of the blood.