Which one of the following options correctly describes the principle of the common law rule of in duplum? 1. It refers to damages calculated in terms of the positive interesse. 2. It is seen as compensation assessed with reference to negative interesse on account of breach of contract or misrepresentation inducing a contract. 3. It is aimed at 'supplementing' incomplete or defective performance. 4. It protects the debtor in that if mora interest reaches an amount equal to the capital sum due, it ceases to run