In Erie Railroad Co

In Erie Railroad Co. v. Tompkins, where Tompkins sued a New York company that owned a train that hit him in Pennsylvania:

A) the U.S. Supreme Court said that federal common law must be applied in federal court
B) the U.S. Supreme Court said that since this was a matter of common law involving two states, it was a matter for the state courts, not federal district court
C) the Supreme Court of Pennsylvania said this was a matter of New York common law that must be tried in federal court
D) the Supreme Court of New York said this was a matter of Pennsylvania common law that must be tried in that state
E) none of the other choices are correct