Select the correct sequence for the processing of antigens originated outside of the cell after their ingestion by phagocytes.
a) Phagosome formation, fusion with lysosome, antigen degradation, antigen presentation
b) Antigen presentation, phagosome formation, fusion with lysosome, antigen degradation
c) Antigen degradation, phagosome formation, antigen presentation, fusion with lysosome
d) Fusion with lysosome, phagosome formation, antigen presentation, antigen degradation