To enter the host cell, intracellular bacterial pathogens can induce phagocytosis in cells that are normally nonphagocytic. This is done by two major mechanisms depicted in the following schematic diagrams (A and B). Indicate whether each of the following descriptions better applies to mechanism A or B. Your answer would be a four-letter string composed of letters A and B only, e.g. ABAA.

( ) It is called the zipper mechanism.
( ) It depends on invasin proteins on the surface of the bacterium that bind to their receptors on the surface of the host cell.
( ) It depends on the injection of effector proteins into the host cell by a bacterial secretion system.
( ) It resembles the process of macropinocytosis.