The letter A indicates the _____. A cross section of the eudicot root. Each letter marks a definite structure. Letter A marks the outer layer of the root. Letter B marks the small central region of the root. Letter C marks a structure that surrounds the central region of the root. Letter D marks a cross-like complex in the center of the vascular cylinder, which consists of big oval cells. Letter E marks a layer of the vascular cylinder below the endodermis. The letter A indicates the _____. A cross section of the eudicot root. Each letter marks a definite structure. Letter A marks the outer layer of the root. Letter B marks the small central region of the root. Letter C marks a structure that surrounds the central region of the root. Letter D marks a cross-like complex in the center of the vascular cylinder, which consists of big oval cells. Letter E marks a layer of the vascular cylinder below the endodermis. a) endodermis b) xylem c) epidermis d) vascular f) cylinder g) cortex.