A cell lining the inside of the stomach is producing some digestive enzymes that are to be released into the stomach. Which transport mechanism out of the cell is most likely involved in this process?

exocytosis

a channel protein

endocytosis

simple diffusion

I would have to go with exocytosis. (exo = out) (endo = in)

Exocytosis is the correct answer. Zymogens like pepsinogen are leaving, not entering the cell, so it's not exocytosis. They are too large for channel protein transport or simple diffusion. They are "shipped" outside the cell via vesicular transport into the gastric lumen, where catabolism of proteins can begin.