The correct IUPAC name of \([ \text{Pt}(\text{NH}_3)_2\text{Cl}_2 ]^{2+} \) is:
Diamminedichloridoplatinate (IV)
Step 1: Understanding the IUPAC name. In this compound, platinum is in the +2 oxidation state, and the ligands are ammonia (NH_3) and chloride (Cl^-). The correct IUPAC name is based on the oxidation state of the platinum ion and the ligands attached to it.
Step 2: Conclusion. Thus, the correct IUPAC name is Diamminedichloridoplatinum (II), corresponding to option (A).