Concept:The cation forms a hydroxide that is amphoteric and also forms a soluble complex with excess ammonia.Explanation:Zinc salts give a white precipitate of Zn(OH)2 with NaOH.This precipitate dissolves in excess NaOH to form a soluble zincate complex: [Zn(OH)4]2−.With aqueous ammonia, zinc also gives white Zn(OH)2, which dissolves in excess ammonia to form [Zn(NH3)4]2+.This behaviour is characteristic of Zn2+.Answer:A. Zn