The correct option is A Testis of mammal
A sustentacular cell is a type of cell that provides structural support. They are of two types. One type of cell is found in the Sertoli cell, in the testicle of mammals. It is present in the walls of the seminiferous tubules and supplies nutrients to sperm as the sertoli cell is nurse cell and another type of cells are found in the olfactory epithelium.