An action potential at the axon hillock generates local currents that depolarize nearby sections of axon to threshold. This change in membrane potential causes voltage-gated Na+ channels to open in the adjacent axon segment. This generates/regenerates the action potential in the adjacent segment, causing the action potential to propagate away from the axon hillock.
I think the correct answer from the choices listed above is option C. The function that is both performed by goblet cells and lacrimal glands is protection. They produce mucus in order to protect mucous membranes. Hope this answers the question.
