The correct answer is: A. Railway Board.
The Railway Board is the apex body of the Indian Railways. It is responsible for the overall administration and management of the railways. The Railway Board is headed by the Chairman, who is a member of the Indian Administrative Service. The Railway Board has a number of departments, each of which is responsible for a different aspect of the railways. The General Rules are prepared by the Railway Board. They are a set of rules that govern the working of the railways. The General Rules are binding on all employees of the railways.
The Zonal Railways are the regional units of the Indian Railways. They are responsible for the operation of the railways in their respective regions. The Zonal Railways are headed by a General Manager, who is a member of the Indian Railway Service. The Zonal Railways have a number of departments, each of which is responsible for a different aspect of the railways. The General Rules are not prepared by the Zonal Railways.
The PCOM is the Principal Chief Mechanical Engineer. He is responsible for the maintenance and repair of the rolling stock of the Indian Railways. The PCOM is a member of the Indian Railway Service. The PCOM does not prepare the General Rules.
The GM is the General Manager of a Zonal Railway. He is responsible for the operation of the railways in his respective region. The GM is a member of the Indian Railway Service. The GM does not prepare the General Rules.