**Question:** The only neurons showing action potential are

A. Purkinje cells
B. Motor neurons
C. Sensory neurons
D. Neurons in the central nervous system (CNS)

**Core Concept:** An action potential is a rapid, transient change in membrane potential of a neuron, allowing for the transmission of an electrical signal along the neuron's axon.

**Why the Correct Answer is Right:** Neurons in the central nervous system (CNS), specifically neurons in the somatic, autonomic, and sensory systems, display action potential. Action potentials are essential for the transmission of signals within the nervous system, allowing for communication between neurons and other cells.

**Why Each Wrong Option is Incorrect:**

A. Purkinje cells are a type of neuron in the cerebellum, primarily involved in motor coordination and balance. They do not generate action potentials, as they do not have the necessary structure (axons and dendrites) for signal transmission.

B. Motor neurons, like Purkinje cells, are involved in motor functions but do not exclusively show action potentials. Motor neurons transmit signals from the spinal cord to the muscles, allowing muscle contraction.

C. Sensory neurons are responsible for transmitting sensory information from the body to the central nervous system and do not solely exhibit action potentials. While they generate action potentials upon receiving stimuli, they do not solely rely on action potentials as they also communicate through neurotransmitters.

D. Neurons in the central nervous system (CNS) are specifically involved in transmitting signals within the nervous system. Action potentials are essential for this communication, allowing for coordinated responses in the body.

**Clinical Pearl:** Understanding the role of action potentials helps in comprehending neural communication and the functioning of the nervous system. In clinical practice, this knowledge is crucial for diagnosing and treating neurological disorders affecting neuronal communication.