Explanation:

- Option 1: Is not liable to compensate that another

- This means the person does not have to pay or compensate for the benefit received.

- ? This is incorrect under Indian Contract Act Section 70 (Non-Gratuitous Act).

- Option 2: Is liable to compensate that another

- This means the person must pay or compensate the other for the benefit enjoyed.

- Correct Answer: If someone lawfully does something for another, not intending to do it for free, and the other person enjoys the benefit, they must compensate.

- Option 3: Has to perform the same non–gratuitous act in return

- This would mean doing the same act for the first person, which is not a legal requirement in such cases.

- Option 4: None of the above

- This would mean none fit, but that's incorrect.