Option b is the correct answer. During the reign of Alauddin Khalji, the Khalisa land was developed extensively. Khalisa land referred to the crown land directly controlled by the ruler. Alauddin implemented a series of land and agrarian reforms aimed at consolidating his power and ensuring a stable revenue source. He abolished the iqta system, which was a system of granting land to nobles in return for military service. He brought all land under the direct control of the state and made it the basis of his revenue system. The Khalisa land was cultivated by peasants who paid rent to the state. The revenue from the Khalisa land was used to finance Alauddin Khalji's military campaigns and other projects. Alauddin's administration recruited efficient revenue officials, audited accounts, and imposed severe punishments for corruption. This systematic approach led to the expansion and development of the Khalisa land under his rule.