Under what condition does the woman say she will attend John's party?

The woman indicates that she will attend John's party "if she finishes work in time." This condition reveals that her attendance at the party hinges on her ability to complete her work before the party starts. It highlights the importance of managing her responsibilities and implies a time-sensitive situation.

While the other options present possible scenarios that might also affect her decision (such as her health, transportation, or the timing of her work), the phrasing of the correct choice emphasizes the direct relationship between the completion of work and her decision to attend the party. Thus, the answer reflects a clear condition tied to her work obligations.