The IUPAC name 2,3-dibromo-1-phenylpentane indicates that:
- There is a phenyl group attached to the first carbon of the pentane chain.
- Bromine atoms are attached to the second and third carbons of the chain.
In the options provided, structure 3 matches this description, with a phenyl group at the first carbon and bromine atoms at the second and third carbons.
Thus, the correct structure is: Structure 3