How Does Tramadol Help Control Pain

How does tramadol help control pain?

A) Binding to opioid receptors in the brain to reduce the perception of pain
B) Reducing the inflammatory substances at the site of injury to inhibit the actual cause of the pain
C) Binding to adrenergic receptors in the spinal cord preventing pain signals from reaching the brain
D) Inhibiting the generation of nerve impulses along the peripheral sensory nerves to alter the transmission of pain