The complex tetraammine copper (II) ions are formed when a salt is treated with an excess of ammonium hydroxide. The salt in question contains cupric ions. Let's break down the process and explain why the correct answer is option 'C'.

1. Formation of a Complex:
- When a salt is treated with excess ammonium hydroxide, the ammonia molecules act as ligands and form a complex with the metal ions present in the salt.
- In this case, the metal ion is copper (II) ion (Cu2+).
- The ammonia ligands coordinate with the copper (II) ion to form a complex called tetraammine copper (II) ions.
- The formula of this complex is [Cu(NH3)4]2+.

2. Identification of the Metal Ion:
- To determine the metal ion present in the starting salt, we need to consider the anion of the salt.
- The question does not provide information about the anion, so we cannot determine the exact salt.
- However, since the complex formed contains copper (II) ions, the starting salt must contain cupric ions (Cu2+).
- Therefore, the correct answer is option 'C' - cupric ions.

3. Explanation of Other Options:
a) Cuprous ions: Cuprous ions have a +1 charge (Cu+). However, the complex formed in this reaction contains copper (II) ions with a +2 charge (Cu2+), so cuprous ions are not present in the salt.
b) Chloride ions: Chloride ions (Cl-) are not involved in the formation of the complex. The complex is formed by the coordination of ammonia ligands with copper (II) ions.
d) Calcium ions: Calcium ions (Ca2+) are not involved in the reaction. The formation of the complex is specific to copper (II) ions.

In conclusion, when a salt is treated with excess ammonium hydroxide, it forms a complex tetraammine copper (II) ions. The starting salt contains cupric ions, and the correct answer is option 'C'.