Sachs, from California, Bought a Ticket to Ride the Train

Sachs, from California, bought a ticket to ride the train (OBB) in Austria. The government of Austria owns OBB. When trying to board a train, Sachs fell to the tracks and both legs were crushed. She sued OBB for negligence in court in the United States. OBB claimed sovereign immunity. The Supreme Court held that OBB:

A) ​had to defend the suit in the United States because it sold tickets in the United States, making it a commercial activity in the country.
B) ​had to defend the suit in the United States because a train is not part of the central government of Austria, such as the legislature, so is subject to normal litigation.
C) ​did not have to defend the suit in the United States because Austrian law forbid such actions.
D) ​did not have to defend the suit in court in the United States because such actions must go to court in Austria under rules of sovereign immunity.
E) ​none of the other answers are correct.