It is always single layered structure in dicot root.
A. Epidermis
B. Endodermis
C. Pericycle
D. Exodermis
Usually the epidermis and endodermis are single layered structures of dicot root. Pericycle is few layered. The hypodermal region of cortex with suberised cell walls is called exodermis. It is also more than one layered.