Which statement describes capillary action?

The correct statement regarding capillary action is that it involves the movement of liquid through thin pores or tubes due to surface tension and adhesion. Capillary action occurs when liquid is drawn into narrow spaces against the force of gravity, primarily due to the attractive forces between the liquid molecules and the surrounding solid surfaces. In the context of porous materials, this phenomenon is critical in understanding how water moves through soils, building materials, and various substrates.

This process is essential in fields such as hydrology, material science, and restoration, as it plays a significant role in how moisture interacts with different materials. For example, when water enters the tiny pores of a material, adhesion causes water to climb up into these spaces, allowing it to permeate various structures.

The other options describe different phenomena: vapor diffusion refers to water vapor movement; absorption involves materials that take in moisture due to their hygroscopic properties; and evaporation involves the transition of water from a liquid to a vapor state. Each of these processes contributes to moisture dynamics but does not specifically define capillary action as its essence is in the movement facilitated by surface tension and adhesion in narrow spaces.