The correct option is D All of the above
If both nitrogen and sulphur are present in an organic compound, Sodium thiocyanate is formed in the sodium extract.
Na+C+N+S⟶NaSCN
When the sodium extract containing SCN− ion is treated with FeCl3 solution, it gives blood red colouration by formation of [Fe(SCN)]2+
Fe3++SCN−⟶[Fe(SCN)]2+Blood red colour
If sodium fusion is carried out with an excess of sodium, then the sodium thiocyanate formed is further decomposed to yield cyanide and sulphide. Cyanide and sulphide ions give their usual tests.
NaSCN+2NaΔ⟶NaCN+Na2S
Thus, statement (a), (b) and (c) are correct.