Which pair of metal ions in their respective oxidation states forms colourless compounds?

• A
  $Zn^{2+}$ and $Cu^{+}$
• B
  $Cu^{2+}$ and $Sc^{3+}$
• C
  $Ti^{4+}$ and $Mn^{2+}$
• D
  $Mn^{3+}$ and $Ni^{2+}$