Explanation

A reflex action is a rapid, automatic response to a stimulus.

The simplest reflex arc involves only two neurons:

1. Sensory neuron (afferent): carries information from the receptor to the spinal cord
2. Motor neuron (efferent): carries the response from the spinal cord to the effector (muscle or gland)

Key Point:

The longest reflex pathway involves multiple neurons.

It is called a "long reflex" or " polysynaptic reflex".