Let's evaluate each statement regarding the 73rd Constitutional Amendment (Panchayati Raj): a. Provides four-tier Panchayati Raj System: Incorrect. The amendment mandates a three-tier system (village, intermediate, and district levels) in states with a population above 20 lakhs. States below this population threshold may choose not to have the intermediate level. It does not provide for a four-tier system. b. Assured duration of five years: Correct. Article 243E provides a fixed tenure of five years for every Panchayat from the date of its first meeting. c. Devolution of powers to Panchayats is vested with the Union Government: Incorrect. Article 243G leaves the devolution of powers, authority, and responsibilities to Panchayats to the State Legislatures. The Union Government provides guidelines and financial assistance through schemes, but the constitutional power for devolution rests with the states. d. Gram Sabha is the foundation of the Panchayati Raj System: Correct. Article 243A provides for a Gram Sabha at the village level, consisting of all adult voters registered in the Panchayat area. It is conceptualized as the base unit and foundation of the system. Therefore, only statements b and d are correct.