(C) Between 1990 and 2015, the number of interstate motor carriers increased from 346,000 to 746,142; at each five-year interval, the number of interstate motor carriers was greater than it was at the previous time. The correct answer is not choice (A) because the number of marine vessel operators varied during this period. It is not choice (B) because between 1990 and 1995, the number of air carriers increased. It is not choice (D) because between 2010 and 2015, the number of marine vessel operators increased.
