Final answer:
Phagosome formation is the step in phagocytosis where engulfment of a microbe occurs, leading to phagosome creation inside the phagocyte.
Step-by-step explanation:
The step in the mechanism of phagocytosis that involves the engulfing of a microbe and the formation of a phagosome in the cytoplasm of the phagocyte is d) Phagosome formation. After a phagocyte, like a macrophage, recognizes and adheres to the microbe, it extends its plasma membrane to envelop the microbe. This results in the internalization of the microbe within a newly formed intracellular vesicle known as a phagosome. The phagosome then fuses with a lysosome, creating a phagolysosome where the microbe is destroyed by hydrolytic enzymes and acidic conditions.