What is the role of leaves in photosynthesis?

Leaves serve as the primary site for photosynthesis due to their large surface area, which is crucial for optimizing the absorption of sunlight. The expansive surface allows for a greater number of chloroplasts—tiny organelles responsible for photosynthesis—to be present, enhancing the leaf's ability to capture light energy. Additionally, the structure of leaves includes numerous stomata, which facilitate gas exchange, allowing carbon dioxide to enter and oxygen to exit, thus supporting the photosynthetic process. The flat shape and thinness of leaves also contribute to this efficiency, minimizing the distance that gases must diffuse and maximizing light capture while providing a significant area for the chlorophyll pigment to absorb sunlight.

While leaves have other functions, such as regulating water loss and storing nutrients, their primary role in photosynthesis hinges on maximizing light absorption through their design. This is why the selection highlighting their large surface area as the key feature for photosynthesis is correct.