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The most widely accepted theory for ascent of sap in trees is

1. capillarity
2. role of atmospheric pressure
3. pulsating action of living cell
4. transpiration pull and cohesion theory of Dixon and Jolly

Correct answer: transpiration pull and cohesion theory of Dixon and Jolly

Solution

The ascent of sap is best explained by the transpiration pull and cohesion theory because transpiration from leaves creates a negative pressure that pulls water upward. Cohesion between water molecules and adhesion to xylem walls help maintain a continuous water column, making this the most accepted mechanism.

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