The option C “the force of root pressure” is the main force by which most of the water within xylem vessels moves towards the top of a tree.
The movement of ions and fluids from the soil to the upper parts of a plant is cause by a driving force called root pressure or hydrostatic pressure.
This movement takes place spontaneously in the upward direction in the xylem tissues of the plants that are responsible for the transport of ions, minerals and water vapors.
Moreover, osmotic pressure also plays a huge role in the process of root pressure.
If you need to learn more about xylem click here:
https://brainly.com/question/14197052
#SPJ4