The chelating ligand used in the treatment of lead poisoning is

The correct answer is Option (3) → EDTA

Chelating ligands bind a metal ion through several donor atoms and form stable complexes, so they can remove a toxic metal from the body. EDTA is used in the treatment of lead poisoning: it binds \( \ce{Pb^{2+}} \) as a stable chelate, which is then excreted.

NCERT (2026-27 edition):
Importance and Applications of Coordination Compounds – “… There is growing interest in the use of chelate therapy in medicinal chemistry. An example is the treatment of problems caused by the presence of metals in toxic proportions in plant/animal systems. Thus, excess of copper and iron are removed by the chelating ligands D–penicillamine and desferrioxime B via the formation of coordination compounds. EDTA is used in the treatment of lead poisoning. Some coordination compounds of platinum effectively inhibit the growth of tumours. Examples are: cis–platin and related compounds.”