Option 1: The greenness of the tree gives the cool feeling. This statement is incorrect. The color of the tree does not have a direct impact on the temperature you feel.

Option 2: Photosynthesis absorbs heat. This statement is incorrect. Photosynthesis is a process where plants convert sunlight into energy, but it does not directly affect the temperature around the tree.

Option 3: The leaves convert water vapors into water, which is a heat-absorbing process. This statement is incorrect. While transpiration (the process by which plants release water vapor) does have a cooling effect on the plant itself, it does not directly affect the temperature around the tree.

Option 4: The leaves give out water, which vaporizes, absorbing some heat as latent heat. This statement is correct. When plants release water through transpiration, the process of water vaporization absorbs heat from the surroundings. This leads to a cooling effect under the tree as the surrounding air is cooled by the evaporation of the water released by the leaves.

In conclusion, option 4 is the correct answer. The leaves of the tree giving out water which vaporizes, absorbing some heat as latent heat, is the reason why you feel cooler under a tree compared to a tin