Law on Obligations and Contracts: Answer the following and NO PLAGIA.

Question 4

Regan is obliged to give an Iphone 4 to Mary. However, Regan have many Iphone 6 in his possessions but does not have and Iphone 4 so he delivered and Iphone 6 instead to Mary. The Iphone 6 is much better and more expensive than the Iphone 4. Upon learning that Regan delivered and Iphone 6, Mary refused to accept it and demanded an Iphone 4. Due to this dispute, they approached their mayor for advice. The Mayor then advised them that Regan deliver an Iphone 6 to Mary and compel her to accept it instead of an Iphone 4 since the former is better. Is the advice of the mayor legally correct? Explain.