To solve this problem, we need to understand the nature of the ethylene diaminetetraacetate (EDTA) ion.$\newline$EDTA is a well-known chelating agent used in coordination chemistry.$\newline$Let's analyze its structure and properties:$\newline$• EDTA is a hexadentate ligand, meaning it can form six bonds with a metal ion.$\newline$• The structure of EDTA includes four carboxylate groups and two amine groups.$\newline$• The four carboxylate groups provide four oxygen donor atoms.$\newline$• The two amine groups provide two nitrogen donor atoms.$\newline$Therefore, EDTA has a total of six donor atoms: four oxygen and two nitrogen.$\newline$This allows EDTA to form very stable complexes with metal ions by occupying six coordination sites.$\newline$Analyzing the options:$\newline$• Option 1: Hexadentate ligand with four “O” and two “N” donor atoms. This is correct.$\newline$• Option 2: Unidentate ligand. This is incorrect as EDTA is not unidentate.$\newline$• Option 3: Bidentate ligand with two “N” donor atoms. This is incorrect as EDTA is hexadentate.$\newline$• Option 4: Tridentate ligand with three “N” donor atoms. This is incorrect as EDTA has two nitrogen donor atoms.$\newline$Therefore, the correct option is Option 1.