Which from following compounds can be obtained by azo coupling reaction.

The azo coupling reaction involves arenediazonium salts acting as electrophiles with electron-rich aromatic compounds like phenols.

P-Hydroxyazobenzene forms when benzenediazonium chloride couples with phenol at the para position relative to the hydroxyl group, yielding $\mathrm{C_6 H_5 N=NC_6 H_4 OH}$.

Other options are inconsistent: benzenediazonium chloride is a reactant; fluoroarenes result from Balz-Schiemann reactions; N-ethylbenzene sulfonamide derives from sulfonyl chloride and amine reactions.