The correct answer is a) myelinated.
Myelinated neurons have a fatty sheath called myelin that surrounds their axons. This myelin acts as an insulator and allows electrical impulses to travel much faster along the axon. The myelin sheath is not continuous; it is segmented with gaps called Nodes of Ranvier. When an impulse travels down a myelinated neuron, it jumps from one node to the next, a process known as saltatory conduction. This jumping significantly increases the speed of nerve impulse transmission compared to unmyelinated neurons, where the impulse travels more slowly along the entire membrane without jumping between nodes.