What is the correct structure for 7-bromo-5-octyn-3-one?

The correct structure is shown below,

According to rules the longest carbon chain is selected, and numbering is started from side nearer to carbonyl group. As the parent name goes to ketone, so among alkyne and halogen second priority is given to alkyne and 3rd to halogen

So, the name shoul carry following words,

3 - one (for ketone)

5-yne (for Alkyne)

7-Bromo (for Halogen)

Result:

So the structure is as follow,