(N/A) The ascent of xylem sap is primarily driven by the transpirational pull,which is supported by the following physical properties of water:
$1$. Cohesion: This is the mutual attraction between water molecules due to hydrogen bonding.
$2$. Adhesion: This refers to the attraction of water molecules to the polar surfaces of the xylem vessel walls (tracheary elements).
$3$. Surface Tension: Water molecules are more attracted to each other in the liquid phase than to water molecules in the gaseous phase,which gives water high tensile strength.
$4$. Capillarity: This is the ability of water to rise in thin tubes,facilitated by the small diameter of the tracheids and vessel elements.
These properties collectively provide water with high tensile strength and high capillarity,enabling it to be pulled upward through the xylem against the force of gravity.