Final answer:
In most prevalent to least: The order of WBC types is neutrophils, lymphocytes, monocytes, eosinophils, and basophils, denoting their presence in the bloodstream and role in the immune response.
Step-by-step explanation:
White Blood Cells (WBCs), or leukocytes, play an essential role in the immune system by defending the body against invading pathogens. These cells vary in prevalence in the bloodstream. Neutrophils are the most abundant type of granulocytes, and they are followed by lymphocytes, which can be either agranulocyte or granulocyte, but are often considered separately due to their unique functions. Then come the monocytes, which are the largest type of white blood cell and are part of the agranulocyte family.
Following them are eosinophils, and the least prevalent are basophils. Basophils are granulocytes and are the rarest of the WBCs, comprising less than one percent of the total leukocyte count. In summary, the order from most prevalent to least prevalent is neutrophils, lymphocytes, monocytes, eosinophils, and basophils.