Thousands of years ago, traveling was very hard. There were no roads and no cars. People traveled on rivers and lakes. They used logs, either one at a time, or tied together.
People then began to use animals to pull very heavy loads. Some people put rollers under a load, and this was the first use of the wheel. The wheel was the most important invention in transportation.
The need to transport many people at one time led to the use of the stagecoach. It's a horse-drawn public vehicle carrying passengers along a regular route. The stagecoach was pulled by four to six horses. It often rode through the night with a change of a driver.
But people wanted a faster and easier way of traveling. The 'horseless carriage' of automobile was invented in 1892. Life became more pleasant. Roads were built. Farmers were able to travel to cities. City people were able to get fresh fruits and vegetables. People traveled to many places for fun.
The main idea of the first paragraph is that ______.
A．people traveled on lakes thousands of years ago
B．people used logs thousands of years ago
C．traveling was hard thousands of years ago
D．there were no roads and cars thousands of years ago