The correct answer is option (A), Rohtas.
According to the 2011 census, the percentage of irrigated land in Rohtas district is 68.9%. This is the lowest among all the districts in Bihar. The other districts in the list have a higher percentage of irrigated land: Buxar (72.2%), Begusarai (73.4%), and Gopalganj (74.1%).
There are a number of factors that contribute to the low percentage of irrigated land in Rohtas district. One factor is the lack of access to irrigation water. The district is located in a semi-arid region, and there is a limited amount of surface water available for irrigation. In addition, the district has a low rainfall, and the monsoon rains are often erratic. This makes it difficult to rely on rain-fed agriculture.
Another factor that contributes to the low percentage of irrigated land in Rohtas district is the lack of irrigation infrastructure. The district has a small number of canals and tube wells, and these are often in poor condition. This makes it difficult to irrigate large areas of land.
The low percentage of irrigated land in Rohtas district has a number of negative consequences. One consequence is that it limits the types of crops that can be grown in the district. Only crops that are drought-tolerant can be grown without irrigation. This limits the variety of crops that are available to farmers, and it also reduces the potential yields of these crops.
Another consequence of the low percentage of irrigated land in Rohtas district is that it makes it difficult to increase agricultural production. Without irrigation, farmers are limited in the amount of land that they can cultivate. This makes it difficult to meet the growing demand for food in the district.
The low percentage of irrigated land in Rohtas district is a major challenge for the district. The government needs to invest in irrigation infrastructure and improve access to irrigation water. This will help to increase agricultural production and improve the livelihoods of farmers in the district.