The dam which is not used in the gezira is the

None of the options provided, including A swan, are a dam in the Gezira region of Sudan. However, among the major dams in Sudan, the one that is not located in Gezira is the Jebel Azulia Dam. This dam is located on the Blue Nile in the Northern state of Sudan, about 25 kilometers north of the capital city of Khartoum. The Gezira region of Sudan is known for its large irrigation scheme, which utilizes water from the Blue Nile to cultivate various crops. The region has two major dams that are used for irrigation, namely the Sennar and Roseires dams. Therefore, if the question specifically refers to dams in the Gezira region, the answer would be either Sennar or Roseires.