(ii) Lassaigne extract give + ve test with $\mathrm{AgNO}_{3} .$ So $\mathrm{Cl}$ is present, -ve test with $\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}$ means $\mathrm{N}$ is absent. So it can't be Aspartame or Saccharine or Alitame, so $\mathrm{C}$ is sucralose.

(iii) Lassaigne solution of $B$ and $D$ given $+ve$ sodium nitroprusside test, so it is having $S$, so it is Saccharine and Alitame.