Besides Qutub Minar, which other monument was built by Qutub-ud-din-Aibak?
(A) Alai Darwaza
(B) Siri Fort
(C) Hauz Khas
(D) Quwwat-ul-Islam Mosque

Hint: This monument is built using gray quartz, white marble, and red sandstone. It was best known for the tower of victory situated in it which is symbolized as a celebration of Muslim conquest in Indian territory.

Complete answer:
Qutub-ud-din Aibak was raised as a slave in Nishapur. He worked for Mu’izz al-din who after winning conquest in India gave him charge of the territory. After the death of Mu’izz al-din, he took over the charge of the Indian territory independently, and thus Muslim rule came into India with the establishment of the Slave dynasty. He had led several conquests against Rajputs and united many Indian territories under his control including Bengal and Bihar. He had financed the very famous Qutub Minar, also known as the victory tower. Along with Qutub Minar, a mosque named Quwwat-ul-Islam was also built by him next to Qutub Minar. The expansion of this mosque continued even after his death by the forthcoming rulers. It was built by using the ruins of 27 Jain and Hindu temples. This mosque is the first one to be built in the Indian territory after the victory of Muslims in India. The site on which the mosque has been built was a place where there was a Jain temple but after the Muslim conquest, this place was used as a mosque.

So the correct answer is (D) Quwwat-ul-Islam Mosque. Besides Qutub Minar, the other monument built by Qutub-ud-din-Aibak was Quwwat-ul-Islam Mosque.

Note: the Quwwat-ul-Islam mosque is located in Delhi and is also known as Qutub mosque or the Great Mosque of Delhi.