Atropine competes with acetylcholine at its receptor sites. Black widow spider venom releases excess acetylcholine. Classify each of these two substances as an agonist or an antagonist. A) Atropine is an agonist and black widow spider venom is an antagonist. B) Atropine is an antagonist and black widow spider venom is an agonist C Both are agonists. D) Both are antagonists.
