Step 3: Review the specific functions of the leukocytes listed in the problem: Eosinophils, Basophils, Neutrophils, and Monocytes. Each type has a distinct role in the immune system. For example, eosinophils are involved in combating parasitic infections, neutrophils are the first responders to bacterial infections, and monocytes differentiate into macrophages to engulf pathogens.