In Southern Pacific Co v. Arizona, concerned whether Arizona could, for safety considerations, ...

In Southern Pacific Co v. Arizona, concerned whether Arizona could, for safety considerations, require trains traveling through the state be a shorter length than trains traveling through other states. The Supreme Court held the Arizona law was valid:
 a. because it concerned a legitimate state interest to improve transportation safety b. because Congress had not passed legislation dealing with the length of trains
  c. because it did not conflict with federal standards d. because it only applied to intrastate trains
  e. none of the other choices