Final answer:
The organism that prevents the fusion of a phagosome with a lysosome after phagocytosis is Mycobacterium tuberculosis. Therefore correct option is C
Step-by-step explanation:
The organism that is an intracellular pathogen capable of preventing fusion of a phagosome with a lysosome after phagocytosis has occurred is Mycobacterium tuberculosis. This bacterium produces a waxy substance called mycolic acid in its cell envelope, which enables it to resist some of the killing mechanisms within the phagolysosome after being engulfed by phagocytes in the lung.
On the other hand, Legionella pneumophila and other bacteria like Salmonella species use a mechanism to evade digestion by preventing the fusion of the phagosome with the lysosome, thus they can remain alive and multiply within the phagosome.