Explanation:

- The doctrine of Part Performance (under Section 53A of the Transfer of Property Act, 1882) is a defense used in property disputes.

- It protects a person who has performed their part of an unregistered contract for the transfer of immovable property.

- The doctrine is only used as a shield, not a sword—meaning it can only be used as a defense and not to bring an action.

- Only the defendant can use this doctrine to protect their possession or interest in the property if the other party tries to wrongly dispossess them.

- It cannot be used by a plaintiff to claim possession or title.

- Unborn persons cannot use it as they do not have legal capacity.

- Option 1: Both Defendant-Plaintiff

- Option 2: Only Plaintiff

- Option 3: Only defendant

- Option 4: Unborn Person