Which detail is LEAST relevant to the overall meaning of the passage?

A) Acupuncture needles are metallic, solid, and hair-thin.
B) Acupuncture should only be performed by trained and licensed practitioners.

C) When not delivered properly, acupuncture can cause serious adverse effects, including infections and punctured organs.

D) Improper needle placement, movement of the patient, or a defect in the needle can cause soreness and pain during treatment.