The correct option is
C benzene diazonium chloride
Hydrolysis of calcium carbide yields ethyne.
CaC2+2H2O→C2H2+Ca(OH)2
Now, in the presence of red hot copper tube, 3 molecules of ethyne polymerize to give benzene.
3C2H2 + red hot Cu tube →C6H6 (benzene)
In the presence of HNO3−H2SO4, nitration of benzene occurs (electrophilic aromatic substitution) and nitrobenzene is formed.
C6H6+HNO3−H2SO4→C6H5NO2 (nitrobenzene)
In the presence of Fe−HCl, nitrobenzene reduces to aniline.
C6H5NO2+Fe−HCl→C6H5NH2 (aniline)
Aniline on reaction with NaNO2−HCl gives benzene diazonium chloride.
C6H5NH2+NaNO2−HCl→C6H5N+2Cl−
The complete reaction sequence is as follows:
CaC2Hydrolysis−−−−−−→C2H2Redhot−−−−→CutubeC6H6HNO3−H2SO4−−−−−−−−−→50−600CC6H5NO2Fe+HCl−−−−−→C6H5NH2
NaNO2+HCl,0oC−−−−−−−−−−−→C6H5N+2Cl−
Therefore, E is benzene diazonium chloride.