The first kind of air transportation was not a plane. It was a balloon. People traveled by balloon 100 years before there were planes or jet aircraft. Those early days of ballooning were exciting, but they were also dangerous. Sometimes the balloons fell suddenly. Sometimes they burned. However, the danger did not stop the balloonists. The first real balloon flight was in France in 1783. Two Frenchmen, the Montgolfier brothers, made a balloon. They filled a very large paper bag with hot air.  Hot air is lighter than cold air, so it goes up. The Montgolfier's hot air balloon went up 1,000 feet in the sky. Later that same year, two other Frenchmen ascended   in a basket under a balloon. They built a fire under the balloon to make the air hot. This made the balloon stay up in the air for a few hours. But their balloon was tied to the ground. So it could not go anywhere. The first free balloon flight was in December, 1783. The balloon flew for 25 minutes over Paris. It traveled about 5.5 miles. Flying a balloon is not like flying a plane. The balloon has no engine and therefore no power of its own. The wind directs the balloon. It goes where the wind blows. The pilot can control only the altitude of the balloon to find the right wind direction. That is how a good pilot controls where the balloons goes. Soon balloonists tried longer flights. A major event in the history of ballooning was the first long flight over water. In 1785, an American and a Frenchman flew over the English Channel. During the nineteenth century, ballooning became a popular sport. There were balloon races in Europe. Balloons were also used by scientists to study the air and by armies in wartime. After the airplane was invented, people lost interest in balloons. Planes were much faster and easier to control.  But some people today still like to go up in balloons. High up in the balloon basket, they find quietness. They have wonderful view of the world below. One way to control a balloon is to  _  .
use the engine find the right wind direction ask the pilot not change altitude
Question: The first kind of air transportation was not a plane. It was a balloon. People traveled by balloon 100 years before there were planes or jet aircraft. Those early days of ballooning were exciting, but they were also dangerous. Sometimes the balloons fell suddenly. Sometimes they burned. However, the danger did not stop the balloonists. The first real balloon flight was in France in 1783. Two Frenchmen, the Montgolfier brothers, made a balloon. They filled a very large paper bag with hot air.  Hot air is lighter than cold air, so it goes up. The Montgolfier's hot air balloon went up 1,000 feet in the sky. Later that same year, two other Frenchmen ascended   in a basket under a balloon. They built a fire under the balloon to make the air hot. This made the balloon stay up in the air for a few hours. But their balloon was tied to the ground. So it could not go anywhere. The first free balloon flight was in December, 1783. The balloon flew for 25 minutes over Paris. It traveled about 5.5 miles. Flying a balloon is not like flying a plane. The balloon has no engine and therefore no power of its own. The wind directs the balloon. It goes where the wind blows. The pilot can control only the altitude of the balloon to find the right wind direction. That is how a good pilot controls where the balloons goes. Soon balloonists tried longer flights. A major event in the history of ballooning was the first long flight over water. In 1785, an American and a Frenchman flew over the English Channel. During the nineteenth century, ballooning became a popular sport. There were balloon races in Europe. Balloons were also used by scientists to study the air and by armies in wartime. After the airplane was invented, people lost interest in balloons. Planes were much faster and easier to control.  But some people today still like to go up in balloons. High up in the balloon basket, they find quietness. They have wonderful view of the world below. One way to control a balloon is to  _  .
A. use the engine
B. find the right wind direction
C. ask the pilot
D. not change altitude
Answer: