A、Animal. B、Rollers. C、Wheel. D、Load. C

Thousands of years ego, travelling was very hard. There were no roads and no cars. People travelled on rivers and lakes. They used logs, either one at a time or put them 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 wheel. The wheel was tile most important invention in transportation.
    The need to transport many people at one time led to the stagecoach. The stagecoach was pulled by’ four or six horses. It often rode through the night with a change of a driver.
    But people wanted a faster and all easier way of travelling. "The horseless carriage" or car 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.