Low polarisation and hence electro valency is favoured by which set of cations:

Options

A. Lantharides cations : `ce^(3+), Eu^(2+)`
B. Post transition metal cations: `Tl^+, Pb^(2+), Bi^(3+)`
C. Transition metal cations : `Ti^(3+), V^(3+),Cr^(2+), Mn^(2+),Cu^+`
D. S-block cations : `Na^+,K^+,Mg^(++),Ca^(++)`