I NEED HELP! I don’t get it

Answer:
A is upper epidermis.
B is palisade mesophyll
C is empty spaces
D is stomata cell
E is lower epidermis
Explanation:
This diagram is the structure of leaf. Lower and upper epidermis is the boundary of the leaf. Stomata are present on the lower epidermis. There are a lot of empty spaces in the leaves. The main function of palisade mesophyll is the absorption of sunlight and uses this light during photosynthesis process.