Sodium thiosulphate $(Na_2S_2O_3 \cdot 5H_2O)$ is used in photography to

If a didentate ligand ethane-$1, 2$-diamine is progressively added in the molar ratio $en : Ni :: 1: 1, 2: 1, 3: 1$ to $[Ni(H_2O)_6]^{2+}$ aqueous solution,the following coordination entities are formed:
$I$. $[Ni(H_2O)_4en]^{2+}_{(aq)} -$ pale blue
$II$. $[Ni(H_2O)_2(en)_2]^{2+}_{(aq)} -$ blue/purple
$III$. $[Ni(en)_3]^{2+}_{(aq)} -$ violet
The wavelengths in $nm$ of light absorbed in the case of $I$ and $III$ are respectively:

The compound that inhibits the growth of tumors is

The reagent used for the detection of $Ni^{2+}$ is $A$. $x$ moles of $A$ react with $Ni^{2+}$ to form a complex of $C$ color. $A$,$x$,and $C$ are respectively:

To inhibit the growth of tumours,identify the compounds used from the following:
$(A)$ $EDTA$
$(B)$ Coordination Compounds of $Pt$
$(C)$ $D$-Penicillamine
$(D)$ $Cis-Platin$
Choose the correct answer from the option given below:

$EDTA$ is used in the estimation of