Consider the following statements with respect to the Panchayati Raj in India :

1. The Ashok Mehta Committee suggested a two-tier structure of Panchayati Raj. 

2. Providing reservation for backward classes is a compulsory requirement by the 73rd amendment to the Constitution enacted in 1992.

3. Some provisions of the 73rd constitutional amendment have been left to be decided by respective State Legislatures at their discretion. 

Which of the statements given above is/are correct?