The main function of stomata is to

A) expose the chlorophyll to sunlight.
B) transport water to the chlorophyll.
C) allow passage of CO₂ and O₂ into the leaf.
D) store glucose.
E) store pyruvate and provide the site of the Calvin cycle.

Stomata are small pores found on the surface of most leaves that allow for gas exchange between the plant and its environment. They open to allow carbon dioxide to enter the leaf for the process of photosynthesis and oxygen to exit. Additionally, they allow water vapor to escape from the leaf during transpiration. CO₂ and O₂ (usually referring to ions such as potassium) can also enter the leaf through stomata to aid in the process of photosynthesis. The other options are incorrect as stomata do not play a direct role in exposing chlorophyll to sunlight, transporting water to chlorophyll, storing glucose or pyruvate, or providing the site of the Calvin cycle.