The correct answer is (b) Superintendent of Police.
The Superintendent of Police (SP) is the head of the police force in a district. He/She is responsible for maintaining law and order in the district. He/She is also responsible for investigating crimes and apprehending criminals.
The District Magistrate (DM) is the chief administrative officer of a district. He/She is responsible for the overall administration of the district. He/She is also responsible for maintaining law and order in the district, but this responsibility is shared with the SP.
The Chief Development Officer (CDO) is the head of the district development administration. He/She is responsible for planning and implementing development projects in the district. He/She is not responsible for maintaining law and order in the district.
The District Revenue Officer (DRO) is the head of the district revenue administration. He/She is responsible for collecting taxes and other revenue from the district. He/She is not responsible for maintaining law and order in the district.