Final answer:
Acetylcholine binds to muscarinic receptors at synapses between post-ganglionic neurons and effector cells in the parasympathetic nervous system.
Step-by-step explanation:
The receptor type that acetylcholine binds to at synapses between post-ganglionic neurons and effector cells in the parasympathetic nervous system is muscarinic. The cholinergic system includes two types of receptors: nicotinic receptors, which are ligand-gated ion channels found on ganglionic neurons, and muscarinic receptors, which are G protein-coupled receptors found on the targets of postganglionic parasympathetic fibers. Muscarinic receptors are not exclusively for depolarization and can have varying effects depending on the type of target cell and the specific muscarinic receptor subtype involved.