The requirement for supreme court decisions issued by the justices is that? a. all nine justices must agree on a case to be decided b. three-fourths of the justices must agree on a case to be decided c. a simple majority is all that is needed to decide a case

The correct option is C.
For a supreme court to hear an appeal case, four of the nine judges must vote to accept the case. For a supreme court decision by the judges to be considered valid, a majority of justices must agree to all the contents of the court's opinion before it is publicly delivered. Justices do this by signing the opinion.