How do Type III secretion systems contribute to pathogenicity?

Type III secretion systems are not virulence factors but do allow microbes to survive harsh environmental conditions.

They are protein channels that allow a microbe to exit phagocytes if they are caught.

They are protein channels that allow a microbe to secrete exoenzymes into the environment to gain nutrients when nutrients are scarce.

They are protein channels that allow a microbe to directly inject cells with toxins.