Prior to the railroad, all of the following made travel difficult in Texas EXCEPT: a. It took weeks to cross the state by stagecoach, and travel was often difficult and dangerous. b. Roads were poorly constructed and extremely muddy during wet weather, which made it difficult for stagecoaches to pass through. c. Severe traffic congestion on the few roads that were available made it difficult to get from one city to the other. d. Rivers were too shallow for ships to travel year-round, making it necessary to travel by stagecoach, which was very slow.