What is the main work of Mansabdari System in Mughal Empire?

The correct answer is Option (4) → Both Military cum Bureaucratic affairs.

The mansabdari system, set up by Akbar, gave every officer of the Mughal state a rank (mansab) with two numbers: zat, his personal rank and salary, and sawar, the number of cavalrymen he had to maintain.

A mansabdar was therefore both a military commander, who kept troops ready for the emperor, and a civil officer who could be posted to run a province, a department or the revenue administration. The system combined military and bureaucratic duties, so neither “only military” nor “only civil” describes it.