The most accurate answer is release water vapor.
Stomata are special pores in plants found typically on the outer leaf skin layer called the epidermis. They consist of two specialized cells called guard cells that surround a tiny pore called a stoma.
Their main function is to allow water vapor and gases such as carbon dioxide and oxygen to move rapidly in and out of the leaf.
The word stomata means mouth in Greek because they allow communication between the internal and external environments of the plant.
