Alright. So this one asks where you would find a cholinergic nicotinic receptor? As a reminder, cholinergic receptors respond to acetylcholine, which is released by all preganglionic fibers in the entire autonomic nervous system. So, we're going to have those nicotinic receptors at the synapse between all preganglionic and postganglionic fibers, again, in the entire ANS, both sympathetic and parasympathetic. So based on that, our answer here is going to be d.
Looking quickly at a through c, so a reads at a parasympathetic effector, and those are going to have cholinergic receptors, but they're not going to be nicotinic. We're actually going to have a video on that coming up, so stay tuned for that. Alright, and then c reads at a sympathetic effector, but those are going to be working with epinephrine and norepinephrine, so those need adrenergic receptors, right?
And then b) it's kind of a trick question because we don't have synapses between two preganglionic fibers, right? We synapse between a preganglionic and a postganglionic fiber. So our answer here is d, and there you go.