Which phrase correctly conveys the idea that a project cannot be completed in one week?

The phrase "It is impossible to finish this project in one week" effectively communicates the idea that completing the project within that timeframe is not feasible. Using "impossible" indicates that there are definitive constraints—whether they are time, resources, or complexities of the project—that prevent its completion in just one week. This makes it the most straightforward and absolute expression of the inability to meet the one-week deadline.

The other options suggest varying degrees of possibility; for instance, saying it is "possible" or "manageable" implies that completion could occur under certain circumstances, which does not align with the requirement to express that completion cannot happen at all. Similarly, stating that it is "unlikely" introduces doubt without eliminating the possibility entirely, which also does not convey the same certainty as "impossible."