2. About diagnostic nerve blocks, which one of following statements is wrong? (A) May help in locating the origin of pain. (B) Pain originating from malfunctioning CNS pain modulation may also be relieved by a peripheral nerve block. (C) Repeated diagnostic blocks are mandatory before any attempted chemical or physical denervation. (D) Are reliable as prognostic aids for neurolytic procedures. (E) Pain relief from a saline block does not indicate a psychogenic pain or malingered pain.