Basophils are best described as:

• A. They are red blood cells
• B. They do not release histamine
• C. They transport oxygen
• D. They release histamine and are least phagocytic

Answer: (D)

Basophils are white blood cells that play a role in allergic and inflammatory responses. They contain granules packed with histamine and heparin. When activated, basophils release histamine, which leads to vasodilation and increased vascular permeability, helping drive inflammation. They have relatively little phagocytic activity compared with other leukocytes like neutrophils or macrophages, so they are considered among the least phagocytic. This combination—releasing histamine and being poor at phagocytosis—best describes basophils. The other options describe red blood cell functions (like oxygen transport) or deny histamine release, which don’t fit basophil biology.