Answer : 4. "Rajasthan"
Explanation :

1. The oldest evidence of plowing the fields has been found from Kalibanga.

2. It is situated on the banks of Ghaggar (Saraswati) river in Hanumangarh district of northern Rajasthan.

3. Kalibanga was excavated in 1960 by B.B. Lal and B.K. Thapar had started it.

4. Evidence of farming is found from Kalibanga, which is the oldest in the world.

5. Evidence of fire altars are found in a row on a raised platform made of raw bricks.

6. It was first discovered by Amla Nand Ghosh in 1952. B. K Thapar and B. B Lal did excavation work here in 1961-69.