The Rio Grande forms the international border between Texas and Mexico. Over the years, the Rio Grande has changed its course several times. This has led to a
number of disputes between Texas, New Mexico, and Mexico. The Country club
dispute between Texas and New Mexico was decided by the U. S. Supreme Court in
1927.
Why did the Supreme Court act as a trial court in this case?

a. The case involved a federal law
b. The case was between several states as parties.
c. The case was between citizens of different states.
d. The case involved foreign ambassadors and other diplomats.