A.Outer most perisotracum only
B.Outer most periostracum and middle prismatic layers
C.Outer most periostracum, middle prismatic layer and innermost nacreous layers
D.None of these
A.Outer most perisotracum only
B.Outer most periostracum and middle prismatic layers
C.Outer most periostracum, middle prismatic layer and innermost nacreous layers
D.None of these