The correct answer is B) court cases that support the decision.
The most important element in summarizing a Supreme Court majority opinion is "court cases that support the decision."
The majority opinion is when more than half members of the court agree on a judicial opinion. This majority of opinion establishes the final decision of the court and the further explanation on how or why the court made that decision. In the case the judges have different reasons in the resolution, it is said that a plurality of opinion exists.