The correct answer is: A. Departmental
A material train is a type of departmental train that is used to transport materials and supplies to and from different parts of a railway network. It is not a permanent train, and its route and schedule may change depending on the needs of the railway company.
A departmental train is a type of train that is used for non-passenger purposes, such as transporting freight or materials. Departmental trains are typically owned and operated by the railway company, and they are not open to the public.
A permanent train is a type of train that has a fixed route and schedule. Permanent trains are typically used for passenger services, and they are often operated by a private company.
None of these is not a correct answer because a material train is a type of departmental train.