Consider the following statements about the Mansabdari System:

 

1. It was introduced by Akbar to organize his military and administrative structure.
2. Mansabdars were ranked based on the number of troops they could maintain.
3. The system gradually declined during the reign of Aurangzeb.
4. It was replaced by the Iqta System during Shah Jahan's rule.

Which of the above statements are correct?