Explanation:

- Impasse: A situation in which no progress is possible, typically due to disagreement or a deadlock.

- Option 1, Deadlock:

- This term means a situation where no progress can be made.

- It suggests a standstill, similar to an impasse.

- Correct Answer: Deadlock adequately captures the essence of an impasse.

- Option 2, Peaceful:

- Implies tranquility or calmness.

- Not related to a scenario of no progress or deadlock.

- Option 3, Resolution:

- Refers to solving a problem or dispute.

- Opposite of an impasse, as it involves progress.

- Option 4, Harmony:

- Suggests agreement and unity.

- Not synonymous with an impasse or deadlock.