Explanation:

- Option 1: One month - Detentions can sometimes be reviewed earlier, but this is not the maximum limit.

- Option 2: Three months - This is the correct answer. Under Indian law, preventive detention cannot exceed three months unless an advisory board with High Court judges finds sufficient cause for a longer period.

- Option 3: Six months - This is not typically allowed without the advisory board's recommendation.

- Option 4: Two months - This is also not the standard maximum period set by the law.