What is the function of penicillamine?

Penicillamine is primarily recognized for its role as an antidote in cases of copper poisoning. It functions by chelating copper, which means it binds to copper ions in the body, allowing for their excretion through the kidneys. This action helps to reduce copper levels in individuals suffering from conditions such as Wilson's disease, where excessive copper accumulation occurs.

While the other choices refer to different forms of poison treatment or antidotes, they do not accurately represent the specific function of penicillamine. It is not indicated for treating iron toxicity, nor is it effective in cases of ethylene glycol or methanol poisoning. Additionally, it is not a general antidote for all heavy metals, as its chelation effect is primarily selective for copper. Therefore, its established use in copper poisoning underscores why the correct answer is centered on this specific therapeutic application.