The correct option is D Alauddin Khilji
Iqta system as introduced at the start of Delhi Sultanate basically consisted of grant of two kinds of iqtas - large and small. Small iqtas were under khuts and muqaddams who had become quite powerful by Alauddin's reign. Alauddin abolished the system of small iqtas and incorporated them in the khalisa, i.e. the land under the central Govt. This helped in streamlining the administration of the Sultanate.