c
The absorption of visible light and hence coloured nature of the transition metal cation is due to the promotion of one or more unpaired \(-\,d\,-\) electron from a lower to higher will be the number of unpaired electron higher will be the absorption in visible light.

The electronic configuration of the given elements is

\(S{c^{3 + }}(18)\, = \,1{s^2}\,2{s^2}\,2{p^6}\,3{s^2}\,3{p^6}\,3{d^0}\,4{s^0}\)   no unpaired \(e^-\)

\(T{i^{4 + }}(18)\, = \,1{s^2}\,2{s^2}\,2{p^6}\,3{s^2}\,3{p^6}\,3{d^0}\,4{s^0}\)   no unpaired \(e^-\)

\({V^{3 + }}(18)\, = \,1{s^2}\,2{s^2}\,2{p^6}\,3{s^2}\,3{p^6}\,3{d^2}\,4{s^0}\)  - Two unpaired \(e^-\).

\(Z{n^{2 + }}(28)\, = \,1{s^2}\,2{s^2}\,2{p^6}\,3{s^2}\,3{p^6}\,3{d^{10}}\,4{s^0}\)   no unpaired \(e^-\)  

hence \([V(NH_3)_6]^{3+}\) will moost likely absorb visible light.