How can you rephrase 'You won't succeed unless you try harder' using 'until'?

The chosen rephrasing effectively conveys the original message that success is contingent on increasing one's efforts. Using "until" in this context emphasizes that success is not merely a possibility; rather, it is a condition that cannot be met without the requisite effort. The phrase captures the essence of the idea that without making a stronger attempt, success remains out of reach, maintaining the original causative relationship between trying harder and succeeding.

This construction aligns closely with the meaning of the original sentence, clearly indicating that success will only come after an increase in effort. The other options do not maintain this critical relationship quite as effectively. For example, some alternatives suggest that success happens or might happen without the same emphasis on the necessity of greater effort, which dilutes the original intent of the statement.