Explanation: The evolution of Delhi as a significant urban center is a complex and layered process that began in the late 12th and early 13th centuries. To understand this, it is essential to delve into the historical context and the key events that shaped the city's development.
Delhi's history can be traced back to the Indus Valley Civilization, but its evolution as a major urban center began with the establishment of the Chauhan dynasty in the late 12th century. The Chauhan ruler, Prithviraj Chauhan, built the Qila Rai Pithora, which is considered the first significant urban settlement in Delhi. This marked the beginning of Delhi's transformation into a major city.
In the early 13th century, the Delhi Sultanate was established, which further propelled the city's growth. The Delhi Sultanate was a series of Muslim dynasties that ruled over large parts of the Indian subcontinent from the early 13th to the early 16th century. The first dynasty, the Mamluk dynasty, was founded by Qutb-ud-din Aibak, who continued the construction of the Qutub Minar, which was initiated by his predecessor, Qutb-ud-din Aybak. This period saw the construction of several important architectural landmarks, including the Quwwat-ul-Islam Mosque and the Alai Darwaza.
The subsequent dynasties, including the Khalji, Tughlaq, Sayyid, and Lodi dynasties, further contributed to the city's development. Each dynasty left its mark on Delhi through the construction of new cities and architectural marvels. For example, the Tughlaq dynasty built Tughlaqabad, which was the fourth city of Delhi, and the Lodi dynasty built the Lodi Gardens, which are now a popular tourist attraction.
The evolution of Delhi as a significant urban center was not limited to the 13th century. The city continued to grow and evolve under the Mughal Empire, which ruled from the early 16th to the mid-19th century. The Mughals built several new cities, including Shahjahanabad, which is now known as Old Delhi. The Mughal period saw the construction of iconic structures such as the Red Fort and the Jama Masjid.
In summary, the evolution of Delhi as a significant urban center began in the late 12th and early 13th centuries, with the establishment of the Chauhan dynasty and the Delhi Sultanate. This period laid the foundation for the city's growth and development, which continued under subsequent dynasties and the Mughal Empire. Therefore, the correct answer is (D) Only (A) & (B), as both the late 12th and early 13th centuries mark the beginning of Delhi's significant urban evolution.