Read the passage. Then answer the questions.
Camels and the American Desert
1. In 1803, the Louisiana Purchase nearly doubled the size of the United States, but Europeans and Americans had never fully explored the area. The U.S. government sent expeditions to observe the land and make maps. In 1820, one group explored areas that are now in New Mexico and Texas. It was a very dry year. They had trouble finding water in the area they explored. They said that much of the West was a desert and a harsh environment for people to live in.
2. Nevertheless, many people wanted to move to the West. Traders took a long and dangerous route to trade with Spanish settlers in Santa Fe, New Mexico. Mules and horses had a hard time surviving the journey. The U.S. Army decided to conduct an experiment. The Army wanted to see if camels could help troops and settlers in the West.
3. In 1856, a U.S. Navy ship sailed to North Africa and brought back thirty-three camels and a few men to handle the camels. On their first trip in the American desert, the camels showed that they were very strong and didn't need much water. They also ate plants along the way. Travelers didn't have to carry camel food or search to find food or water. The Army decided to buy forty-one more camels. In the next few years, camels joined several caravans to California.
4. But within a few years, the camels were set free or sold. They were very good at carrying loads over harsh land, but Americans didn't like them. They smelled bad and frightened the horses. Americans liked to handle mules and oxen instead of camels. Mules and oxen responded to orders more quickly and easily.
5. The Army never purchased any more camels. Other people who brought camel herds into the United States weren't successful either. Camels were probably the best animals for crossing Western deserts, but Americans used horses, mules, and oxen instead. Most Americans never learned to get along with camels.
This question has two parts. First, answer Part A. Then answer Part B.
Part A Which sentence states the main idea of the passage?