Which chelating ligand is used to remove excess $Cu$ poisoning in plants and animals?

Which of the following compounds is used as an anti-cancer agent?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$K_4[Fe(CN)_6] + ZnSO_4 \longrightarrow Zn_2[Fe(CN)_6] \downarrow + 2K_2SO_4$

In a complexometric titration of a metal ion with a ligand,the reaction is $M$ $(Metal-ion)$ + $L$ $(Ligand)$ $\to$ $C$ $(Complex)$. The end point is estimated spectrophotometrically (through light absorption). If '$M$' and '$C$' do not absorb light and only '$L$' absorbs,then the titration plot between absorbed light $(A)$ versus the volume of ligand '$L$' $(V)$ would look like:

Which of the following is considered as an anticancer species?

What metal is present in Wilkinson's catalyst,which is used as a homogeneous catalyst for the hydrogenation of alkenes?