The correct answer is option 2: Stomata. Stomata are tiny pores that are present on the surface of leaves in plants. These pores allow for the exchange of gases, such as carbon dioxide and oxygen, as well as the release of water vapor. Stomata play a crucial role in photosynthesis, as they enable the intake of carbon dioxide needed for the process. They also aid in regulating the water balance in plants, as they can open and close to control the transpiration rate. Pits (option 1) are depressions on the surface of plants but are not specifically related to leaf structure. Trichomes (option 3) are hair-like structures found on the surface of leaves, stems, and other plant parts. Hydathodes (option 4) are specialized pore-like structures that excrete water droplets in some plants.