The passage of water through a selectively permeable membrane from a less concentraded region to a more concentrated region is called

I believe the answer for the above question is Osmosis. It is the net movement of water molecules through a selectively permeable membrane, from a region of greater water concentration to a region of lesser water concentration. It is the diffusion of water through a selectively permeable membrane. It occurs when two solutions of different solute concentration are separated by a selectively permeable membrane. 

Iwould say silver and gold