Hint: Delhi Sultanate refers to various Muslim dynasties that governed India from 1210 A.D. to 1526 A.D. It was established when Muhamad Ghori defeated Prithvi Raj in the second battle of Tarain that was fought in 1192 A.D.
Complete answer: The nobles were a very powerful class during the Delhi Sultanate period. Most of them belonged to a Turkish origin. All the high ranks in the sultanate like military commanders or provincial governors consisted of the noble class. The nobles occupied a place next to the Sultan and played a great role in the administration of the state. Nobles consisted of the aristocracy and belonged to different tribes and countries like Turkish, Persian, Arabic, Egyptian and Indian Muslims. The Hindu nobles in the Sultanate period were negligible. They had important functions in the Empire:
-They helped the sultans in expanding the empire.
-They also helped sultans in suppressing the rebellions of the Hindus.
-They helped the Sultan in the smooth functioning of the empire.
-They also played a crucial role in the choice of Sultan.
The Corps of forty was the council of 40 Turkic and non - Turkic nobles that was administered under the Delhi Sultanate. It was formed by Qutb-al-Din Aibak but later was modified by Sultan Iltutmish. It was the first ministerial body formed in India.
Thus, option D is the correct answer.
Note: Due to the rivalry between the nobles which led to the end of the Lodi dynasty and beginning of the Mughal rule in India as the nobles extended an invitation to Babur to invade the Lodi dynasty and Babur was also successful in destroying the Corps of the forty group.