The coordination complex must be neutral. Here in all the options, the oxidation states of Pt are given such that we get an overall neutral complex. Again, while naming a complex, the cationic part should be named first followed by the anionic part. While naming the anionic part, the name of the metal should end with the suffix -ate. From this, we can conclude that the IUPAC name of [Pt(NH3)4][PtCl4] can be either (A) or (D). But the most common oxidation state of Pt is +2 and +4 and in both the parts of the complex, Pt has the same coordination number, and so, the correct option will be (D).