What does the Supreme Court ruling in Immigration and Naturalization Service v. Chadha illustrate about Supreme Court rulings?

a. The rulings automatically become the law of the land and each of the branches has an obligation to enforce the decision.
b. The rulings are submitted to the states for approval and if three quarters approve, the decision becomes binding on the country.
c. The absence of enforcement authority has allowed Congress and the President at times to ignore Supreme Court rulings.
d. Congress must pass a law that codifies the Supreme Court decision so it can officially be added to the U.S. Code.

c. The absence of enforcement authority has allowed Congress and the President at times to ignore Supreme Court rulings.