Phagocytosis event sequence

Steps:

• Event 1: Pathogen binds to phagocyte membrane, initiating recognition.
• Event 2: Phagocyte engulfs pathogen, forming phagosome vesicle.
• Event 4: Lysosomes move and fuse with phagosome to form phagolysosome.
• Event 3: Lysosomal enzymes hydrolyze pathogen contents for digestion.

Why B is correct:

• Phagocytosis follows attachment (1), engulfment (2), fusion (4), then enzymatic digestion (3), per standard cellular biology process.

Why the others are wrong:

• A: Places fusion (4) before engulfment (2), impossible without phagosome.
• C: Starts with digestion (3), which requires prior steps.
• D: Begins with digestion (3) and ends with binding (1), reversing the process.

Final answer: B