Final answer:
Plant C with the highest number of stomata per cm² is the most likely to be found in a rainforest due to the need for rapid gas exchange in environments with ample water and light where the risk of dehydration is lower.
Step-by-step explanation:
Among the given plants, Plant C, with the highest average number of stomata per cm² at 103,800, would most likely be found growing in a rainforest where there is an abundance of water and sunlight. High stomatal density is beneficial in such environments because it allows for rapid gas exchange to support high rates of photosynthesis under ample light and water conditions. Conversely, plants with fewer stomata are often adapted to conserve water in dry environments.
Stomata are surrounded by guard cells that regulate opening and closing in response to environmental conditions such as light intensity, water status, and carbon dioxide concentrations. Plants must balance the need for uptake of carbon dioxide for photosynthesis against the risk of excess water loss. In moist, humid rainforest conditions, the risk of dehydration is lower, so plants can afford to have more stomata for efficient photosynthesis.