Which specific force between water molecules helps maintain a continuous water column in xylem vessels?

Correct answer: Cohesive force

Correct answer: B, cohesive force. Cohesion is the attraction between molecules of the same substance. Water molecules attract one another through hydrogen bonding, so they tend to remain connected as a continuous column inside narrow xylem vessels. Transpiration from leaves creates tension that pulls this column upward, while cohesion helps transmit that pull through the water. A adhesion is attraction between unlike substances, such as water and the xylem wall; it also assists ascent but is not the force specifically asked for between water molecules. C gravity pulls downward and opposes ascent. D is not the standard biological term for maintaining the xylem water column. Cue: cohesion means same-with-same; adhesion means water-with-wall.