Here's why:

* Passive transport refers to the movement of molecules across a cell membrane without requiring the cell to expend energy. This movement is driven by the concentration gradient (from an area of high concentration to an area of low concentration).

* Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration. This applies to the movement of both solutes (dissolved substances) and solvents (the substance that dissolves the solute, like water).

* Osmosis is a specific type of diffusion that involves the movement of water molecules across a semi-permeable membrane from a region of higher water concentration to a region of lower water concentration.

Let me know if you'd like to explore these concepts in more detail!