How Did the 2013 Supreme Court Ruling Invalidate the Heart

How did the 2013 Supreme Court ruling invalidate the heart of the Voting Rights Act of 1965?

A) The entire act was declared unconstitutional, since evidence of racial bias in southern election law no longer met the Court's burden of proof standard.
B) The southern states cited in the original law no longer needed approval from the Justice Department before changing their election laws.
C) The Court threw out the law's original provision providing federal protection for African-American voters at the polls in four southern states.
D) Limitations were removed from the range of acceptable voter identification required for same-day registration at the polls.
E) The Court declared that literacy tests were no longer necessary.