The correct option is D (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
The Lassaigne's test helps to detect nitrogen, sulphur phosphorous and halogens in the organic compounds. Here, organic compound is fused with sodium metal inside a fusion tube and is converted to ionic state.
Copper(II) oxide reacts with carbon and produces CO2.
Silver nitrate test is done specifically for the detection of halogens. This test results in the formation of silver halides.
When the sodium fusion extract gives black precipitate with acetic acid & lead acetate precipitate with acetic acid and lead acetate, then presence of sulphur is confirmed.
Example: Na2Ssodium fusion extract + (CH3COO)2Pb → PbS + 2CH3COONa
So, the answer will be (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)