\(3 d ^{0} \quad 3 d ^{10}\)

(B) \(Ti ^{4+}, Cu ^{2+}\)

    \(3 d ^{0} \quad 3 d ^{9}\)

(C) \(V ^{2+}, Ti ^{3+}\)

      \(3 d^{3} \quad 3 d^{1}\)

(D) \(Zn ^{2+}, Mn ^{2+}\)

      \(3 d^{10} 3 d^{5}\)

No \(d-d\) transitions in ions with \(d^{0}\) and \(d^{10}\) configuration. Therefore they are colourless.