Please, someone help me! Why is the case of Marbury v. Madison significant?

Select one:

a. It was the last time that the U. S. Supreme Court ruled a law unconstitutional.

b. It was the case that ended segregation in the United States.

c. It was the case that started segregation in the United States.

d. It was the first time that the U. S. Supreme Court ruled a law unconstitutional.