What does the term "capillary action" refer to?

The term "capillary action" specifically refers to the phenomenon where water rises in narrow spaces, such as the tiny gaps between soil particles or within porous materials. This occurs due to the adhesive properties of water molecules, which are attracted to the surfaces of the material, combined with its cohesive properties that allow it to stick to itself. When water encounters a small opening or a narrow tube, the intermolecular forces between the liquid and the solid surfaces enable the water to move upward against the force of gravity.

This concept is essential in various fields, including biology, where it explains how plants draw water from the soil through their roots and transport it to their leaves, as well as in construction, where understanding capillary action can help in assessing moisture movement through building materials. The other options relate to water movement and absorption but do not specifically define the unique process of capillary action.