The correct answer is - D. horse or mule carriages and steam-powered trolleys.
Prior to the 1900's the main transportation sources in the cities were the horse and mule carriages and the steam-powered trolleys. Most of the intercity transport was taken out by the horse and mule carriages which dominated the streets of the cities, they were still the easiest, most efficient, and cheapest transport. The only competition of the carriages were the steam-powered trolleys, and they were the most technologically advanced transportation for intercity transport at this period of time.
