Answer: a. over a dispute involving a U.S. company arising over a dispute within the borders of the U.S.
Step-by-step explanation:
US courts have jurisdiction over Americans and American territory. The strongest case therefore would be one both involving an American company and one on American territory as is the scenario here.
The other two cases might be more difficult to assume jurisdiction over because in option B's case, the companies might be bound by other laws and in option c's case, the US company is in the jurisdiction of another country.