37. Regarding the actions of spinal and supraspinal analgesia for opioids, which of the following statement is most likely: (A) Opioid receptors are mostly located at a predominantly 70% postsynaptic location on the central terminals of only small diameter nociceptive primary afferents. (B) The contribution of kappa, delta and mu receptors to the total opiate binding throughout the spinal cord is estimated to be delta ＞ mu ＞kappa.(C) Opioids inhibit OFF cells via GABA neurons and activate ON cells in the rostromedial medulla (RVM) leading to changes in spinal descending controls. (D) Nitric oxide (NO) is required for the 5-HT-mediated inhibition of PAG output and reversal of antinociception. (E) Fibers descending from the PAG to the dorsal horn of the spinal cord are mostly enkephalinergic, glycinergic and GABAergic.