The hyperalgesia that is common in phantom limb pain could potentially be blocked if a new drug was developed that could prevent (without triggering any side-effects) the
a) binding of enkephalins to nmda receptors
b) diffusion of calcium ions through nmda receptors
c) release of enkephalins diffusion of enkephalins
d) across synaptic clefts

The answer is B- Diffusion of calcium ions through NMDA receptors.

Explanation:

Phantom limb pain (PLP) is a painful sensation experienced after the loss or amputation of a limb. The limb is no longer there but the individual can still feel real and severe pains in the limb. This occurs soon after surgery.

NMDA is a receptor for Glutamate which is an excitatory neurotransmitter. The activation of NMDA receptors are associated with hyperalgesia which is an abnormally heightened sensitivity to pain.

answer axon terminal,synaptic cleft; and motor end plate;