What Is the Point of Original Jurisdiction for Most Litigation

What is the point of original jurisdiction for most litigation in the federal courts?

A) the Supreme Court
B) the U.S.district courts
C) the U.S.Court of Federal Claims -Consider This: The Court of Federal Claims is a legislative court created to handle specialized cases within a particular area of jurisdiction whereas the court in question handles cases pertaining to a diversity of areas.
D) the U.S.courts of appeals