Final answer:
In normal adult bone marrow, the most common granulocyte is the neutrophil, which is the most abundant type of granulocyte and plays a vital role as a first-responder in the body's immune response.
Step-by-step explanation:
In normal adult bone marrow, the most common granulocyte is the neutrophil. Granulocytes, which include neutrophils, eosinophils, and basophils, are a type of leukocyte or white blood cell with a lobed nucleus and granular inclusions in their cytoplasm. These cells are crucial first-responders during injury or infection and have a short lifespan of hours to days. Neutrophils are produced in the red bone marrow and are the most abundant type of granulocyte, followed by eosinophils and basophils, the latter being the least common.
The other options given in the question, eosinophils and basophils, are less common than neutrophils. Monocytes are not classified as granulocytes; they are agranular leukocytes, which become macrophages or dendritic cells upon maturation and play a role in the immune response.