The correct option is D myelin sheath is discontinuous
Myelin sheath along axon is not a continuous sheath, there are gaps between the myelin sheath and these gaps between two adjacent myelin sheaths are called Nodes of Ranvier.
Neurilemma is the cytoplasmic sheath of Schwan cells that is present around the myelin sheath of axon and it is continuous and present over the nodes of Ranvier. Axolemma is the cell membrane of the axon.