Which type of cell is an eosinophil?

An eosinophil is classified as a type of white blood cell that plays a crucial role in the immune system, particularly in responses to allergens, parasitic infections, and asthma. These cells demonstrate a distinct ability to stain with eosin, a specific dye that identifies them among other leukocytes. This staining characteristic is significant in clinical settings, as it allows laboratory professionals to identify and count eosinophil levels in blood samples, providing insights into various health conditions.

Understanding the characteristics of eosinophils is vital, as they are part of the body's defense mechanism and participate in mediating inflammatory responses. The other options describe unrelated concepts—such as blood disorders, pathogens, and cancers—making it clear that the defining feature of eosinophils is their role as a specific type of white blood cell, identifiable through their staining properties.