Correct statement in the following
A) ${\mathrm{Na}}_2\mathrm{EDTA}$ is used to remove ${\mathrm{Ca}}^{+2},{\mathrm{Mg}}^{+2}$ ions from hard water
B) The oxidation number of Ni in the complex formed in the refining of Ni by Mond’s process is +2
C) The oxidation state of Rh in Wilkinson catalyst is +1 
D) D-pencillamine, desferrioxime-B are used to remove excess of lead
E) Cis-platin is used for the treatment of cancer