Explanation:

- Lament: To express sorrow or grief; often used in the context of mourning a loss or a tragic event.

- Option 1, torment: Implies causing intense physical or mental suffering. It's more about inflicting pain rather than expressing sorrow about it.

- Option 2, afflict: Means to cause pain or suffering to someone or something. This word also focuses more on causing pain rather than expressing it.

- Option 3, distress: Describes extreme anxiety, sorrow, or pain. It indicates a state of suffering but isn't specifically about expressing grief.

- Option 4, mourn: To feel or express deep sorrow or grief, typically for someone’s death.

The most appropriate synonym for "lament" is mourn.

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