The correct answer is A. Rohtas.
Rohtas is the least irrigated district by tubewells in Bihar. In 2018-19, only 10.3% of the agricultural land in Rohtas was irrigated by tubewells, compared to the state average of 27.8%. This is due to a number of factors, including the low groundwater table in Rohtas, the high cost of installing and operating tubewells, and the lack of access to electricity in many parts of the district.
Araria is the second least irrigated district by tubewells in Bihar, with only 11.4% of its agricultural land irrigated by tubewells. Samastipur is the third least irrigated district, with 12.2% of its agricultural land irrigated by tubewells. Gaya is the fourth least irrigated district, with 12.6% of its agricultural land irrigated by tubewells.
The following are some of the reasons why Rohtas is the least irrigated district by tubewells in Bihar:
- The groundwater table in Rohtas is low. This means that it is difficult and expensive to extract water from the ground using tubewells.
- The cost of installing and operating tubewells is high. This is because the cost of electricity is high in Bihar, and the cost of diesel, which is used to power some tubewells, is also high.
- Many parts of Rohtas do not have access to electricity. This means that farmers in these areas cannot use tubewells to irrigate their crops.
The government of Bihar has taken some steps to increase the use of tubewells in Rohtas. For example, the government has provided subsidies to farmers who install tubewells. However, these measures have not been enough to significantly increase the use of tubewells in the district.