Correct answer: C. Alauddin Khalji
Explanation: The correct answer is Alauddin Khalji. After becoming Sultan of Delhi, he planned to construct the Alai Minar near the Qutb Minar in the Qutb complex. His intention was to build a tower much larger and taller than the existing Qutb Minar, thereby displaying his authority and military success. However, the project remained incomplete, and only its massive lower base survives today. Iltutmish is associated with completing and expanding the Qutb Minar, while Balban and Sikandar Lodi were not responsible for this unfinished monument. Thus, the name Alai Minar should be directly connected with Alauddin Khalji and the medieval architecture of the Delhi Sultanate.