A blue solution of salt X gives no precipitate with dilute $\mathrm{HCl}$. Passing $\mathrm{H}{}_2\mathrm{S}$ through the acidified solution gives a black precipitate Y, which dissolves in hot dilute $\mathrm{HNO}{}_3$ leaving a pale yellow solid and giving a blue solution Z. Z gives a deep blue species W with excess $\mathrm{NH}{}_3$. The identity of Y and the spin-only magnetic moment of the cation in W (in BM, using $\sqrt{n(n+2)}$) are

1. A$\mathrm{CuS}$, 0 BM
2. B$\mathrm{CuS}$, 2.83 BM
3. C$\mathrm{PbS}$, 1.73 BM
4. D$\mathrm{CuS}$, 1.73 BM