The correct option is D Structure of Lenticel
The given figure shows the structure of lenticel.
Lenticel: One of many raised pores in the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues.
It is the lense shaped pores which are found in the bark of woody plants. It functions as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases.
They develop from woody stems when the epidermis is substituted by the bark or cork. Lenticels in woody plants appear as cork-like, rough structures on the young branches. The porous tissues under these generate many intercellular spaces between cells.