b
In \(TiF _{6}^{2-}\) titanium is in \(+4\) state. In \(\mathrm{Cu}_{2} \mathrm{Cl}_{2}\) the copper is in \(+1\) state. Thus in both cases, transition from one d-orbital to other is not possible.

\(\mathrm{Ti}-3 d^{2} 4 s^{2} \rightarrow \mathrm{Ti}^{4+}-3 d^{0} 4 s^{0}\)

\(\mathrm{Cu}-3 d^{10} 4 s^{1} \rightarrow \mathrm{Cu}^{+}-3 d^{10} 4 s^{0}\)