Answer:
D.II and III only
Explanation:
Monocytes are the agranular leukocytes that serve as precursor of macrophages. When the blood monocytes enter the infected tissue or the site of infection, they are transformed into macrophages to carry out the function of phagocytosis of pathogens and cellular debris. Macrophages are also present in lymphoid tissues such as spleen and lymph nodes to remove the debris and pathogens from the lymph. Hence, macrophages are found in lymph nodes and infected tissues only; not in blood.
