Identify [A], [B], and [C], respectively in the following reaction sequence :

To identify the compounds $$[A]$$, $$[B]$$, and $$[C]$$, we analyze each step of the given reaction sequence involving the transformation of an aromatic amine.

The first step involves the reaction of compound $$[A]$$ with $$NaNO_2/HCl$$ at $$273{-}278\text{ K}$$. These conditions correspond to the diazotization reaction, which is characteristic of primary aromatic amines. Therefore, compound $$[A]$$ must be aniline ($$C_6H_5NH_2$$), which is converted into benzene diazonium chloride.

The benzene diazonium chloride then reacts with $$KI$$. In this reaction, the diazonium group is replaced by an iodine atom with the liberation of nitrogen gas, producing iodobenzene. Hence,

$$[B] = C_6H_5I.$$

In the final step, iodobenzene is treated with sodium metal in dry ether. This is the Wurtz-Fittig reaction, in which two phenyl groups couple together to form biphenyl.

Thus,

$$[C] = C_6H_5{-}C_6H_5.$$

Therefore, the identities of the compounds are:

• $$[A] = \text{Aniline } (C_6H_5NH_2)$$
• $$[B] = \text{Iodobenzene } (C_6H_5I)$$
• $$[C] = \text{Biphenyl } (C_6H_5{-}C_6H_5)$$

Hence, the correct sequence corresponds to the green-checked option shown in the given question.