The United States Supreme Court issues an opinion that can be found at U.S. , 138 S.Ct. 617, 199 L.Ed.2d 501. "617" is

A) the number of the volume in the official reports of the Court's decisions.
B) the number of the volume in an unofficial report of the Court's decisions.
C) a page number in the referenced volume.
D) the number of the case in its chronological sequence.

U.S. Supreme Court

The highest court in the United States, with ultimate appellate jurisdiction over all federal and state court cases that involve a point of federal law.

Official Reports

Comprehensive documents produced by government or other official bodies detailing findings or outcomes of specific investigations or events.

Unofficial Report

An informal or non-validated account or statement concerning an event, situation, or performance.