Explanation:

Statement 1 is not correct as Changez Khan reached Indus during the reign of Iltutmish in 1221 AD,chasing the Khwarizmi prince Jalaluddin.

Statement 2 is correct :The fourth Mongol invasion during Ala-ud-din Khalji reign took place only after some months of Ala-ud-din’s return from Chittor in 1303 A.D. The Mongols numbering 1,20,000 horsemen under the command of Targhi moved so swiftly that provincial governors could not get time to reach Delhi to help the Sultan. Besides, a large part of the army of Ala-ud-din had left for Telingana campaign and the army left at Delhi was insufficient and weak after its tough battle at Chittor. Therefore, Ala-ud-din was not in a position to face the Mongols in an open battle. He retired to the fort of Siri and took up defensive position. The Mongols plundered the environs of Delhi and besieged the fort for two months. But as they were ignorant of the art of siege-warfare, they failed to capture the fort and withdrew.

Hence statement 3 is not correct:The next major Mongol invasion took place after the Khiljis had been replaced by the Tughlaq dynasty in the Sultanate. In 1327 the Mongols invaded under Tarmashirin. Historians have differed regard Muhammad Tughlaq’s policy. According to one version, he defeated the Mongols and himself chased them to drive them out. However according to another version, Muhammad Tughlaq bribed the Mongols and they went back.