Wind speed increases transpiration rate

Steps:

• Transpiration is water loss from leaves via evaporation.
• Wind removes the humid boundary layer around leaves, speeding up evaporation.
• Higher wind speeds thus increase the rate of water loss.
• The graph must show rate rising with wind speed.

Why C is correct:

• Graph C depicts rate increasing with wind speed, aligning with the principle that wind enhances diffusion of water vapor away from leaves.

Why the others are wrong:

• A shows constant rate, ignoring wind's effect on evaporation.
• B shows decreasing rate, contradicting wind's role in accelerating transpiration.
• D shows rate decreasing after an initial rise, unsupported by wind's consistent enhancement.

Final answer: C