What does ingestion and degradation of extracellular antigens and their subsequent presentation by MHC class II molecules lead to

"Activation of CD4+ helper T cells" is the correct choice.

Explanation:

The major complicated of histocompatibility II seems to be the chemical compound for something like the T cells that presets antibodies. Antigens collected from those in the pathogens become transformed as well as inserted into a large histocompatibility system that's also distributed on either the cellular cell surface membrane representing antigen as well as the trigger is perceived by complicated systems of T cells as well as MHC II but rather contained throughout CD4 + support T cells.