ANS:B - Sulphuric acid and napthamine

To detect nitrites in sewage, a common method is the Griess test. In this test, sulfanilic acid and N-(1-naphthyl)ethylenediamine dihydrochloride are combined with the sample. If nitrites are present, they react with sulfanilic acid to form a diazonium salt. Then, the diazonium salt reacts with N-(1-naphthyl)ethylenediamine dihydrochloride to produce a pink azo dye. This pink coloration indicates the presence of nitrites. Therefore, the correct answer is: Sulphuric acid and napthamine.