question: Which of the following type of cementum is located in coronal most region of the tooth where the enamel is covered by the cementum, having a thickness of 1-15 micron:
opa: Acellular afibrilar cementum.
opb: Acellular extrinsic fibre cementum.
opc: Cellular intrinsic fibre cementum.
opd: Cellular mixed stratified cementum.