Final answer:
Capillary action is caused by adhesive forces between a liquid and a surface, combined with cohesive forces within the liquid. These forces allow liquids to climb up capillary tubes, forming a meniscus.
Step-by-step explanation:
Capillary action occurs in liquids because of a combination of adhesive forces and cohesive forces. When a capillary tube, such as a thin glass tube, is placed into a liquid like water, the adhesive forces between the water and the glass pull the liquid up the tube, forming a meniscus. If these adhesive forces are stronger than the cohesive forces—the intermolecular forces holding the liquid molecules together—the liquid rises in the tube, counteracting gravity until an equilibrium is reached. This can be observed in materials with good adhesion to water, such as cotton, and is essential for processes like water transport in plants.
Therefore, the correct answer to why capillary action occurs is Option 1: Due to surface tension and adhesion, which reflects the combination of these forces at work. Surface tension is a result of cohesive forces, and the adhesion between the liquid and the capillary material facilitates the liquid's climb against gravity.