The Group of Forty who advised and assisted the Sultan in administering the Delhi Sultanate was established by which of the following rulers?

The correct answer is Iltutmish.

Explanation and Historical Context:

1. Establishment of Turkan-i-Chahalgani:
Shams-ud-din Iltutmish, the third ruler of the Slave (Mamluk) Dynasty of the Delhi Sultanate, established a group of 40 loyal slave officers known as Turkan-i-Chahalgani or "The Group of Forty" (also called Chalisa). This group was formed to help him administer the Sultanate, maintain control over powerful nobles, and advise him on administrative and state affairs.

2. Key Historical Details:
- Iltutmish ruled from 1211 to 1236 AD and is considered the real consolidator of the Delhi Sultanate.
- The Group of Forty became extremely powerful after the death of Iltutmish and started playing the role of king-makers.
- Later, the powerful Sultan Ghiyasuddin Balban, who himself was originally a member of the Chahalgani, destroyed/abolished the Group of Forty to centralize power and prevent noble revolts.