What is TENS?

TENS is a non-invasive analgesic technique used for the symptomatic management of acute and non-malignant chronic pain.
TENS consists of a method of stimulating peripheral nerves through electrodes attached to the skin for therapeutic purposes.
TENS acts on pain modulating systems, increasing their tolerance to pain by causing analgesia.
TENS uses high-frequency current to alleviate pain.
a) Only statements I, II and III are correct.
b) Only statements II, III and IV are correct.
c) Only statements I, II and IV are correct.
d) All statements are correct.