The correct answer is d) hydrophobicity.
Transpiration is the process by which plants lose water vapor through small openings called stomata. This process relies on several unique properties of water that facilitate the movement and retention of water within plants.
Cohesion refers to the attraction between water molecules, which helps water move upward through plant stems. Adhesion is the attraction between water molecules and other substances, like the walls of plant xylem, aiding in water transport. Capillary action is the ability of water to travel within narrow spaces, which is crucial for pulling water up from the roots to the leaves.
On the other hand, hydrophobicity describes the property of a substance that repels water. This property does not assist in the process of transpiration; in fact, hydrophobic surfaces would hinder water movement rather than promote it. Therefore, hydrophobicity is the special property of water that is not involved in transpiration.