How can anemia be defined?

Anemia is defined as a condition marked by a deficiency of red blood cells or hemoglobin. This definition highlights the impact of anemia on the body’s ability to transport oxygen, as red blood cells and hemoglobin play crucial roles in oxygen delivery to tissues. When there are insufficient red blood cells or reduced levels of hemoglobin, a person may experience symptoms such as fatigue, weakness, and pallor due to inadequate oxygen supply to vital organs.

The other options presented do not accurately describe anemia. Conditions involving excessive blood clotting and high white blood cell counts pertain to different hematological disorders that affect blood coagulation and immune response, respectively. The reference to a disease of the immune system does not encapsulate the primary characteristics of anemia, which focuses on red blood cell and hemoglobin deficiency rather than immune system functions.