The right answer is: dissociate Ach
Cholinesterase is an enzyme, intended to hydrolyze (destroy, break) acetylcholine in the blood, and tissues, into acetic acid and choline. This results in rendering this neuromediator inactive.
Acetylcholine is a neuromediator, a chemical substance (also known as a neurotransmitter) made by the body that allows nerve cells (neurons) to transmit nerve impulses (messages) between themselves or between neuron and another variety of cells of the body (muscles, glands).