Final answer:
The correct statement about Supreme Court decisions is that the reasoning for a court ruling is called the opinion, which requires a majority agreement among the justices.
Step-by-step explanation:
The most accurate statement about Supreme Court decisions among the provided options is c: The reasoning upon which a court ruling was based is known as the opinion. This is the explanation of the justices' decision and includes links to precedent and related cases. The majority opinion is one with which at least five of the nine justices agree. When a case is remanded, it means it is sent back to the lower court for retrial or further action due to a possible error. If a case is reversed by the Supreme Court, the decision of the lower court is overturned but it does not mean it is not subject to any further action. An opinion per curiam is an unsigned opinion by the Court, not necessarily one that all nine justices have signed.