Which category of surface allows liquid to pass through?

The correct answer, porous, refers to materials that contain tiny openings or spaces that enable liquids to flow through them. This characteristic makes porous surfaces capable of absorbing and allowing the passage of fluids. As a result, such materials are used in various applications where permeability is essential, like filtration systems, certain building materials, or natural environments like soil that allows water drainage.

Non-porous surfaces, on the other hand, do not have these openings and do not allow liquids to penetrate, making them waterproof. Semi-porous materials exhibit limited permeability but do not allow liquids to pass through as efficiently as porous surfaces do. Hard surfaces can be either porous or non-porous, but the key aspect defining their permeability is not their hardness but their structural characteristics regarding fluid transfer.