Final answer:
Has air spaces within the leaf - cactus: is (a) Mesophyll.
Step-by-step explanation:
The mesophyll is the internal tissue of the leaf that contains the photosynthetic cells responsible for capturing sunlight and performing photosynthesis. Within the mesophyll, there are two layers: the upper palisade layer and the lower spongy layer.
The upper palisade layer is comprised of tightly packed, columnar cells that are arranged parallel to the leaf surface. These cells contain numerous chloroplasts, which are responsible for carrying out photosynthesis. The tightly packed arrangement of cells in the palisade layer allows for efficient absorption of sunlight.
The lower spongy layer is comprised of loosely packed, irregularly shaped cells. These cells also contain chloroplasts, but are not as densely packed as the cells in the palisade layer. The air spaces between the cells in the spongy layer allow for gas exchange, allowing oxygen to enter and carbon dioxide to exit the leaf through the stomata. Therefore the correct answer is (a) Mesophyll.