Lassaigne’s test gives a violet color with sodium nitroprusside, it indicates

$\underset{\text{ Nitroprusside ion }}{{\mathrm{S}}^{2-}+{\left[\mathrm{Fe}(\mathrm{CN}{)}_5\mathrm{NO}\right]}^{2-}}⟶\underset{\text{ violet color }}{{\left[\mathrm{Fe}(\mathrm{CN}{)}_5\mathrm{NOS}\right]}^{4-}}$

When a few drops of sodium nitroprusside are added to Sodium fusion extract, a rich violet colour emerges, signifying the presence of sulphur. Sulfur detection: nitroprusside causes a violet hue to develop.

Hence, correct option is: (B) S