Dorothy has been suffering from epileptic seizures for the past four years. in the context of neurotransmitter functioning, her seizures can be best attributed to the

In the context of neurotransmitter functioning her seizures can best be attributed to the "overstimulation caused by Glutamate".

Overstimulation of glutamate receptors causes neurodegeneration and neuronal harm through a procedure called excitotoxicity. Unnecessary glutamate, or excitotoxins following up on a similar glutamate receptors, overactivate glutamate receptors (particularly NMDARs), causing large amounts of calcium particles (Ca2+) to inundation into the postsynaptic cell.  

Glutamate excitotoxicity activated by overstimulation of glutamate receptors likewise adds to intracellular oxidative pressure.

the answer is d.index