Statement-1: Zinc ions are not precipitated by ammonia solution as zinc hydroxide, in the presence of ammonium chloride. 

Statement-2: Presence. of ammonium chloride lowers the hydroxyl-ion concentration to such a value that the solubility product of $\mathrm{Zn}(\mathrm{OH}{)}_2$ is not attained.

In the presence of ammonium chloride, zinc ions are not precipitated as zinc hydroxide by ammonia solution. Because the presence of ammonium chloride reduces the hydroxyl-ion concentration to such a low level that the solubility product of zinc hydrooxide is not achieved.

So,statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.
Hence, option A is correct.