Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening, carbon dioxide diffuses into the plant during photosynthesis. Reason out of the above statements using one of the following options.

When a plant is transpiring, its stomata are open, allowing gas exchange between the atmosphere and the leaf. Open stomata allow water vapor to leave the leaf but also allow carbon dioxide (CO2) to enter. Carbon dioxide is needed for photosynthesis to operate. Much more water leaves the leaf than CO2 enters for three reasons: 1. H2O molecules are smaller than CO2 molecules and so they move to their destination faster. 2. CO2 is only about 0.036% of the atmosphere, while water vapor can be much higher. 3. The diffusion coefficient of water vapor in air is greater than that of CO2. Therefore, both processes can happen together because the diffusion coefficient of water and CO2 is different.