The correct answer is option C: Saran.
The Teur canal is a branch canal of the Gandak Canal, which is a major canal in the Indian state of Bihar. The Teur canal irrigates parts of the Saran, Siwan, and Champaran districts of Bihar.
The Teur canal was constructed in the early 1900s. It is about 100 kilometers long and has a command area of about 200,000 hectares. The canal is used to irrigate a variety of crops, including rice, wheat, sugarcane, and maize.
The Teur canal is an important source of irrigation for the people of Saran district. It helps to improve agricultural productivity and reduce poverty in the region.
The other options are incorrect because they are not districts that are irrigated by the Teur canal.