Electrical Stimulation is defined as:

• A. A magnetic field therapy used for joint pain.
• B. An ultrasound technique to promote tissue healing.
• C. A pharmacological intervention delivered via nerve blocks.
• D. Use of a low-voltage electrical current to stimulate nerves for relief of pain.

Answer: (D)

Electrical stimulation means using an electrical current applied to tissues to influence nerve activity in order to relieve pain. The description that uses a low-voltage electrical current to stimulate nerves fits this idea directly, since the goal is to modulate nerve signaling to reduce pain perception. This is the principle behind common pain-relief modalities like TENS, where small electrical currents affect how nerves transmit pain signals.

Other options describe different approaches: magnetic field therapy relies on magnets rather than electrical current; ultrasound uses sound waves for tissue healing rather than nerve stimulation; pharmacological nerve blocks deliver drugs, not electricity, to dampen pain signals. So the low-voltage electrical current option best captures what electrical stimulation is aimed at doing.