D) THICK WAXY CUTICLE
The leaf have adaptations in order to do gas exchange, which are the follwings:
-Large surface area of mesophyll cells
-Interconnecting air spaces in mesophyll
-Many Stomata
A thick waxy cuticle is NOT an adaptation because the waxy cuticle is not thick, is thin, in order to have a short distance for the carbon dioxide to diffuse into the cells.