The correct option is (d).
Explanation
Around 2500 years ago (c. 6th Century BCE), the Ganga-Yamuna doab and surrounding regions witnessed significant economic changes. These changes created an agricultural surplus, which served as the foundation for the Second Urbanisation and the consolidation of large territorial states (Mahajanapadas).
Statement-wise Analysis:
- Statement 1 is Correct: The introduction of the iron ploughshare was a technological breakthrough. It allowed farmers to turn over the heavy, clay-rich soil of the Gangetic plains more effectively than wooden ploughs. This led to a substantial increase in grain production.
- Statement 2 is Correct: Agriculture shifted from scattering seeds to the transplantation of paddy. In this method, saplings were grown separately and then planted in the fields. This significantly increased the survival rate of plants and boosted overall yields, despite being labor-intensive.
- Statement 3 is Correct: To support intensive agriculture and reduce dependency on erratic rainfall, systematic irrigation works were developed. Kings and communities constructed canals, wells, tanks, and artificial lakes to ensure consistent water supply for crops.
Key Takeaway:
The growth of kingdoms and the rise of urban centers in ancient India were primarily driven by an agricultural surplus, enabled by the use of iron tools, paddy transplantation, and organized irrigation.