Cobalt chloride when dissolved in water forms a pink-colored complex $X$ which has an octahedral geometry. This solution,upon treatment with concentrated $HCl$,forms a deep blue complex $Y$ which has a $Z$ geometry. $X$,$Y$,and $Z$,respectively,are:

• A
  $X = [Co(H_2O)_6]^{2+}, Y = [CoCl_4]^{2-}, Z = \text{Tetrahedral}$
• B
  $X = [Co(H_2O)_6]^{2+}, Y = [CoCl_6]^{3-}, Z = \text{Octahedral}$
• C
  $X = [Co(H_2O)_6]^{3+}, Y = [CoCl_6]^{3-}, Z = \text{Octahedral}$
• D
  $X = [Co(H_2O)_4Cl_2]^{+}, Y = [CoCl_4]^{2-}, Z = \text{Tetrahedral}$