which of the two chemicals described next would make the best muscle relaxant and why?

A
B would cause discomfort over time

Are you kidding?

A, of course.

If you flood the muscle cells with Ca++, you practically unlock the tropomyosin.  Actin and myosin starts to slide into each other.  Other words, muscle starts contracting!

SuperFly

I read that... "If drugs are to be used, the most popular ones are carbamazepine, phenytoin, or quinine. "
then I googled and found."Carbamazepine works as an anti-convulsant for partial and grand mal seizures by reducing or blocking certain responses in the brain. It "

then some crap about "
In fact, the muscle relaxants in general, are felt to exert their beneficial effects on the central nervous system (brain and spinal cord), as opposed to a direct effect on skeletal muscle.


 then I got totally confused and wikkipedia'ed it. dang it!

your answer is A.
wiki search yourself. go through less hastle than I did!
here is the good stuff:
"Nondepolarizing agents like tubocurarine block the agonist, acetylcholine, from binding nicotinic receptors and activating them, thereby preventing depolarization. Alternatively, depolarizing agents such as succinylcholine are nicotinic receptor agonists which mimic Ach, block muscle contraction by depolarizing to such an extent that it desensitizes the receptor and it can no longer initiate an action potential and cause muscle contraction.[5]These neuromuscular blocking drugs are structurally similar to acetylcholine, the endogenous ligand, in many cases containing two acetylcholine molecules linked end-to-end by a rigid carbon ring system, as in pancuronium.["