Which is a condition in which the number of erythrocytes blood decreased?

The correct answer is Anemia. Anemia is a condition in which the number of red blood cells or their oxygen-carrying capacity is insufficient to meet the body's needs. Several factors can cause anemia, including blood loss, nutritional deficiencies, bone marrow disorders, and chronic diseases. Symptoms of anemia can include fatigue, weakness, shortness of breath, pale skin, and dizziness. Treatment for anemia depends on the underlying cause and may involve iron supplements, blood transfusions, or medications to stimulate red blood cell production.