The correct answer is: C. Transpiration
Transpiration is the process by which water is lost from the leaves of a plant through tiny pores called stomata. This water loss creates a suction force that draws water up from the roots, through the stem, and into the leaves.
Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration. This process does not require energy and can occur in both living and non-living things.
Photosynthesis is the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen. This process requires energy and takes place in the chloroplasts of plant cells.
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. This process does not require energy and can occur in both living and non-living things.
In conclusion, the ultimate cause of water movement in a plant stem against gravity is transpiration. Transpiration is the process by which water is lost from the leaves of a plant through tiny pores called stomata. This water loss creates a suction force that draws water up from the roots, through the stem, and into the leaves.