The correct answer is: B) nodes of Ranvier.
Schwann cells are non-neural cells that are part of the peripheral nervous system with supportive function for neurons. In myelinated axons, Schwann cells form the myelin sheath that is not continuous. The tiny gaps between adjacent Schwann cells are called nodes of Ranvier.
Nodes of Ranvier are the spots where the axolemma (the cell membrane of an axon) is exposed to the extracellular space. Because of the presence of nodes, nerve conduction in myelinated axons is referred to as saltatory conduction.
