Final answer:
The antidote to beta-blocker poisoning is Glucagon. It works by stimulating the heart and increasing blood glucose levels, which counters the effects of beta-blocker overdose.
Step-by-step explanation:
The antidote to beta-blocker poisoning is D) Glucagon. Beta-blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline, and a high dose can lead to severe poisoning. Glucagon is the antidote of choice because it can bypass the blocked beta-adrenergic receptors and stimulate the heart as well as increase blood glucose levels, which can be beneficial in cases of beta-blocker overdose.
Flumazenil is an antidote for benzodiazepine overdose, not beta-blockers. Naloxone is used to reverse the effects of opioid overdoses. Atropine, while it is used to manage symptoms of nerve agent poisoning and as pre-treatment for some surgeries to reduce saliva, would not be effective against beta-blocker toxicity.