Option B — Only I, II and IV are correct.
Statement III is incorrect because the Municipal chairperson is the head of the Municipality, not Block Samiti.
The textbook clearly states: "Municipalities are set up in towns. Big cities are constituted into municipal corporations. Municipal chairperson is the political head of the municipality. In a municipal corporation, such an officer is called the mayor." Statement III wrongly assigns the Municipal chairperson to Block Samiti (which is a rural, panchayat-level body). Eliminating Statement III rules out options A, C, and D, leaving B as correct.