The correct option is C Both of (A) and (B)
Histogen theory was proposed by Hanstein in 1870. According to this theory, shoot apical meristem consists three distinct zones namely, dermatogen (external layer) which form outer covering of all organ of plant. Periblem (middle layer) which gives rise to cortex and endodermis. Plerome (central layer) which forms pith and primary vascular bundle.
Thus, the correct answer is option C.