Option 1: When martial law is imposed, Parliament cannot make a law to indemnify any person for any act done by them in connection with maintaining order in the area. This means that if someone commits an act in the name of maintaining order during martial law, they cannot be protected or exempted from legal consequences by Parliament.

Option 2: When martial law is in force in an area, Parliament has the power to validate any sentence passed during that time by passing a law. This means that Parliament can make a law to confirm or legitimize the sentences that were given during martial law.

Option 3: Parliament also has the power to validate forfeitures ordered during martial law. This means that any property or assets that were confiscated during martial law can be confirmed as legally taken through a law passed by Parliament.

Option 4: The correct answer is option 4. This option states that any act done under martial law can be validated by Parliament through the law. However, this statement is incorrect. When martial law is in force, Parliament does not have the power to validate any and all acts done during that time.

Alert - correct answer should be: When martial law is imposed, Parliament cannot make a law to validate any act done under martial law.