Here's why:

* Passive transport refers to the movement of substances across a cell membrane without the cell needing to expend energy. This movement is driven by the concentration gradient or pressure gradient.

* Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. This occurs until the molecules are evenly distributed.

* Osmosis is a specific type of diffusion that involves the movement of water across a semi-permeable membrane from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration).

Let me know if you'd like more details on either diffusion or osmosis!