Which of the following is an example of Sandmeyer reaction?

The Sandmeyer reaction is a chemical reaction used to substitute the diazonium group (-N$\equiv$N) in an aromatic diazonium salt with a halogen (Cl, Br, or I) or a cyanide group using a copper(I) halide or cyanide catalyst.

In the given reaction, N$\equiv$$\equiv$N-Cl represents an aromatic diazonium salt. When this compound is heated in the presence of CuCl, the diazonium group is replaced by a chlorine atom, forming an aryl chloride (Ar-Cl) along with the release of nitrogen gas (N$_2$$2$​). This is a classic example of the Sandmeyer reaction, where the copper(I) chloride acts as a catalyst to facilitate the substitution process.

The Sandmeyer reaction is widely used in organic synthesis to introduce halogens into aromatic compounds efficiently.

The reaction between Copper(I)-Halogens, Cyanide, and Diazonium Compounds is known as the Sandmeyer reaction.

Here option D  is an example of Sandmeyer reaction.