Select the CORRECT sentence that uses a conjunction to connect two clauses with different tenses, maintaining coherence and clarity:

Answer: "By the time we arrived, they had already left the party."

"By the time" works as a subordinating conjunction joining two complete clauses, and the tenses differ for a reason: the past perfect ("had left") marks the earlier action, the simple past ("arrived") the later one.

Other options:

Despite finishing her work early, she goes home immediately: "Despite" is a preposition, not a conjunction, so it can't join two clauses. It also has no real tense contrast, and the logic is muddled since finishing early and going home immediately don't oppose each other.

He has finished his studies but is planning to travel next month: Grammatically fine, but "but" links two predicates sharing one subject, not two clauses.

While she cooks dinner, he will be finishing his work in the office: Also grammatically acceptable, though "while she is cooking" would read more naturally for simultaneous action, and the tense contrast is stylistic rather than structurally required.