Plants get water through their roots because of capillarity.

Option 1: Elasticity refers to the ability of a material to stretch or compress, and it is not directly related to the absorption of water by plants.

Option 2: Capillarity is the process by which water is drawn upwards through tiny tubes in the plant`s roots, stems, and leaves. This phenomenon is due to adhesive and cohesive forces in the water molecules, allowing it to move against gravity.

Option 3: Viscosity is a property of fluids that determines their resistance to flow. It does not play a significant role in the uptake of water by plant roots.

Option 4: Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen. While water is an important component for photosynthesis, it is not directly involved in the transport of water through the roots.