In the Citizens United V

In the Citizens United v. Federal Elections Commission (2010) decision, the U.S. Supreme Court ruled that most existing laws and regulations setting limits on campaign donations, and prohibiting corporations and labor unions from endorsing and spending funds to promote political candidates, violated the ______________ of the Constitution.

A) commerce clause
B) necessary and proper clause
C) First Amendment (freedom of assembly)
D) First Amendment (freedom of speech)
E) Fifth Amendment (due process clause)