Answer: b. The Supreme Court ruled that a law passed by Congress was unconstitutional
Step-by-step explanation:
The Principle of Separation of Powers in the US Government is the cause of limited government.
Separation of powers amongst the 3 branches of Government being the Legislative, Executive and the Judiciary means that no one branch has unlimited powers in running the Government as the powers of the other branches can put a check on the other thereby leading to a state of limited government for all 3 branches.
An instance of this is when Congress (Legislative), acting within their mandate, create and pass a law but this law is declared unconstitutional by the Supreme Court (Judiciary) who are there to ensure that the nation abides by the constitution.