Final answer:
The itch receptor has the slowest conduction velocity because its signals are transmitted through thin, unmyelinated axons, resulting in slower transmission speeds compared to the myelinated axons used for proprioception, touch, or myelinated pain signals.
Step-by-step explanation:
The receptor with the slowest conduction velocity is itch. The reason behind this is related to how nerve impulses are conducted along neurons. The slow propagation of an action potential along an unmyelinated axon is known as continuous conduction, which results in a slower transmission speed. Itch sensation, also related to nociception, is carried by thin, unmyelinated axons. Compared to proprioception and touch, which use myelinated axons for faster communication, or myelinated pain fibers, itch fibers conduct impulses more slowly. This means itch signals will reach the cerebral cortex later than those for proprioception, touch, or myelinated pain.