Question: Two hypotheses for stomata density are described. How could you test them?

Sorry I don't know what the hypotheses are :( but below I leave the reading

Leaf stomata are the principal means of gas exchange in vascular plants. Stomata are small pores, typically on the undersides of leaves, that are opened or closed under the control of a pair of banana-shaped cells called guard cells. When open, stomata allow CO2 to enter the leaf, and allow for water and oxygen to escape. In addition to opening and closing the stomata, plants may exert control over their gas exchange rates by varying stomata density in new leaves when they are produced (such as in the spring or summer). The more stomata per unit area is the stomata density.

Why might it be adaptive for a plant to control its rates of water loss and CO2 uptake? One answer can be found in the sun. Increases in heat could denature proteins of membranes of chloroplasts. When overheated, plants may open the stomata to evaporate water to lower the temperature. Based on this, you could hypothesize that leaves in the sun would have a higher stomatal density than leaves in the shade.

On the other hand, if water is not available, such as under drought conditions, excessive evaporation might lead to desiccation (drying out.) Plants in hot areas may benefit from fewer stomata so that they can conserve water.