To solve this problem, we need to identify the reaction and the product formed.$\\$The given reaction involves:$\\$• A diazonium salt $($C$_6$H$_5$N$_2^+$Cl$^-)$ and an aniline derivative $($C$_6$H$_5$NH$_2). \\$This is a typical example of a diazo coupling reaction, which forms azo compounds.$\\$In acidic medium, the diazonium salt reacts with the amino group of aniline to form an azo compound.$\\$The general reaction is:$\\$Ar-N$_2^+$ + Ar'-NH$_2 \rightarrow$Ar-N=N-Ar'-NH$_2 \\$The product is an azo compound with a yellow dye characteristic.$\\$Analyzing the options:$\\$• Option 1: Contains a hydrazine linkage, not typical for diazo coupling.$\\$• Option 2: Incorrect structure, as it does not match the expected azo compound.$\\$• Option 3: Incorrect structure, as it does not match the expected azo compound.$\\$• Option 4: Correct structure, showing the azo linkage between the two aromatic rings.$\\$Therefore, the correct product (A) is represented by Option 4.