Final answer:
Sardar Baghel Singh occupied Delhi in 1790, an event in Sikh history. Further historical details include the execution of Sikh leader Guru Tegh Bahadur, the Islamic Delhi Sultanate, and the Mughals' architectural contributions to Delhi, as well as Meluhha being the Mesopotamian name for the Indus Valley civilization, and the role of citadels in Indus Valley cities.
Step-by-step explanation:
Sardar Baghel Singh, who was a prominent Sikh military leader, occupied Delhi in the year 1790. This historical event is connected to the rich Sikh history in India. As for the other questions presented, Guru Tegh Bahadur, who was executed by Aurangzeb, was a leader of the Sikh religion. The rulers of the Delhi Sultanate followed the Islamic religious tradition, so none of the provided options (Christianity or Buddhism) are correct. Shah Jahan's reign, marked by the move of the Mughal Empire's capital to Delhi and extensive building projects including the Red Fort, signified the Mughal's rich architectural legacy, though the financial strain of these projects had an impact on the local populace.
The term Meluhha was used by the Mesopotamians to refer to the Indus Valley civilization; and in the context of Indus Valley cities, a citadel may have served as the monumental ceremonial center, contrasting with other ancient structures such as ziggurats or pyramids.