By Which Biological Mechanism Does EMDR Achieve Its Therapeutic Effect

By which biological mechanism does EMDR achieve its therapeutic effect?

A) EMDR achieves its therapeutic effect, but the exact biological mechanism is unknown.
B) EMDR achieves its therapeutic effect by causing a decrease in imagery vividness.
C) EMDR achieves its therapeutic effect by causing an increase in memory access.
D) EMDR achieves its therapeutic effect by decreasing trauma associated anxiety.