Final answer:
A miotic drug is pilocarpine, a muscarinic agonist used to treat eye disorders by constricting the pupil and reducing intraocular pressure, and it can also serve as an antidote for atropine and scopolamine poisoning.
Step-by-step explanation:
A miotic drug is A. pilocarpine, which is a muscarinic agonist commonly used to treat eye disorders. Pilocarpine works by causing constriction of the pupil and contraction of the ciliary muscle, leading to drainage of aqueous humor from the anterior compartment of the eye, thus reducing intraocular pressure related to glaucoma. Unlike atropine and scopolamine, which are muscarinic antagonists derived from belladonna and are used for dilating the pupil, pilocarpine constricts the pupil and is used as an antidote for poisoning by these anticholinergic substances.