The correct option is
C facilitating gaseous exchange
Lenticels are lens-shaped apertures found in the bark of trees. Lenticels are filled on the inside with loosely arranged thin-walled cells called complementary cells. Lenticels facilitate the exchange of gases between the outer atmosphere and internal tissues of the stem through intercellular spaces between the complementary cells. Lenticels are formed as a result of secondary growth caused by the phellogen in the extra stelar region.