Answer: The correct answer is- C) macrophages.
Macrophages are a type of phagocytic cell of immune system as they engulf/eat foreign pathogen (such as bacteria) through a process called phagocytosis.
These cells play significant role in initiating the immune response in the body.
They first detect the invading pathogen (foreign substances), after which they engulf and destroy them.
They are produced by differentiation of monocyte when monocyte leave bloodstream and enter specific tissue sites such as spleen, lungs, lymph nodes.