Explanations:The railway repairing unit in Assam is located in Bongaigaon. To understand this, it is important to know the geographical and industrial layout of Assam. Assam, a state in northeastern India, has several important railway junctions and industrial hubs that play a significant role in the state's economy and transportation infrastructure.
Bongaigaon is one such important town in Assam. It is located in the Barpeta district and is known for its industrial activities, including the presence of a railway repairing unit. This unit is responsible for the maintenance and repair of railway equipment and infrastructure in the region. The railway repairing unit is crucial for ensuring the smooth operation of the railway network in Assam, which is vital for both passenger and freight transportation.
Other towns in Assam, such as Digboi and Tinsukia, are also significant but for different reasons. Digboi is renowned for its oil fields and is one of the oldest oil-producing regions in Asia. Tinsukia is a major railway junction and serves as a gateway to the northeastern states of India. However, neither of these towns houses the railway repairing unit.
Hajo, another town mentioned in the options, is known for its religious significance, particularly for the Hayagriva Madhava Temple, which is a major pilgrimage site. It does not have any railway repairing unit.
Therefore, the correct answer is Bongaigaon, as it is the specific location where the railway repairing unit is situated in Assam. This knowledge is essential for those preparing for competitive examinations that test geographical and infrastructure-related knowledge of Indian states.