Which legal document explains the legal reasoning behind a supreme court

It would be "1. The majority opinion" that enables the Supreme Court to make its decision, since it is made up of nine members--meaning that landing on a "tie" is impossible. 

A. democrat, republican, whig, other.(the democratic and republican parties are the main 2 american political parties, the whig party was popular among the early presidents, and the “other” option allows for outliers)