Exp) Option d is the correct answer.

Federalism is a system of government in which entities such as states or provinces share power with a national government.

Statement a is correct. The Constitution establishes an independent judiciary headed by the Supreme Court to settle the disputes between the Centre and the states or between the states.

Statement b is correct. Indian Constitution establishes a dual polity consisting the Union at the Centre and the states at the periphery. Powers have been clearly divided between the Centre and the States under Schedule 7 of the Constitution.

Statement c is correct. States are given representation in the Rajya Sabha on the basis of population. Hence, the membership varies from 1 to 31. Statement d is incorrect. Unlike the United States of America, there has been no agreement between the federating units in India viz. Union and the states.