Option b is the correct answer. The Do-aspa and Sih-aspa system was a system of military ranks introduced by the Mughal emperor Jahangir in the 10th year of his reign ( 1611 CE ). It was a system whereby the selected nobles could be allowed to maintain a larger quota of troopers, without raising their Zat rank. The system was popular as 'du-aspa' (a trooper with two horses) or 'sihaspa' (a trooper with three horses) system. A nobleman with a mansabdar position holding a zat rank of 3000, along with 3000 cavalrymen assigned with the two-horse and three-horse system, would be responsible for overseeing a contingent of 6000 soldiers.