What type of transport method is used for proteins that need to be secreted outside of the cell?

Vesicular transport is the correct method for proteins that need to be secreted outside of the cell. This process involves the encapsulation of proteins in vesicles, which are small membrane-bound structures. These vesicles then travel to the cell membrane, where they fuse with it and release their contents into the extracellular environment.

This transport method is particularly important for the secretion of large molecules, such as proteins and neurotransmitters, which cannot freely cross the lipid bilayer of the cell membrane. Vesicular transport is essential for various cellular functions, including hormone secretion and the release of enzymes.

Other methods, such as passive transport, simple diffusion, and active transport, do not adequately describe the mechanism behind the secretion of proteins. Passive transport and simple diffusion allow only small molecules or ions to move across the membrane without energy input, while active transport involves the movement of substances against their concentration gradient, typically requiring energy, but is not specifically structured for bulk transport like vesicular transport is.