Product C of the following reaction sequence will be

Aniline on reaction with bromine water gives 2,4,6-tribromoaniline (A) as the major product due to the strong activating nature of the $-\text{NH}_2$ group.

Reaction of (A) with $\text{NaNO}_2/\text{HCl}$ at $273-278\text{ K}$ (diazotization) yields 2,4,6-tribromobenzenediazonium chloride (B).

Treatment of (B) with $\text{HBF}_4$ forms 2,4,6-tribromobenzenediazonium fluoroborate. Heating this intermediate with $\text{NaNO}_2$ and $\text{Cu}$ replaces the diazonium group with a nitro group, forming 2,4,6-tribromonitrobenzene (C).

To assign the IUPAC name, we number the ring to give the lowest locant set to the substituents. The set (1, 2, 3, 5) is lower than (1, 2, 4, 6). Therefore, the nitro group is at position 2, and the bromo groups are at positions 1, 3, and 5. The correct IUPAC name is 1,3,5-tribromo-2-nitrobenzene.

Answer: 1, 3, 5-Tribromo-2-nitrobenzene