The answer is: D. iron(II) sulfide.
Iron(II) sulfide is black, water-insoluble solid.
Iron (Fe) is metal and sulfur (S) is nonmetal.
Iron has positive charge 2+ (cations) and sulfur negative charge 2- (anion), which means iron lost two electrons and sulfur gain two electrons.
Balanced chemical reaction: Fe + S → FeS.
