The Supreme Court's Decision in District of Columbia V

The Supreme Court's decision in District of Columbia v.Heller did not rule on the question of incorporating the Second Amendment into the due process clause of the Fourteenth Amendment,at least in part because​

A) ​the justices could not reach an agreement on this issue.
B) ​the District of Columbia is not a state.
C) ​that question had already been answered in a prior decision.
D) ​Justice Scalia persuasively argued that it was not the role of the court to "take certain policy choices off the table."
E) ​liberal justices opposed including this in the decision.