You may picture firefighters holding a hose   outside of a burning building, but the Golden Eagles Hotshots don't fight fires quite that way. When they go into action, you may not even see a fire truck. The Hotshots are firefighters who battle fires in wildness areas. But don't think you'll only find them in their home state California. Wherever there is a national wildfire emergency, the Golden Eagles Hotshots could be there. But these firefighters don't work the same way as firefighters in a big city. They work in areas where there are a large number of trees, bushes, and grass. They climb up and down steep hills to clear brush and burnable debris . They sometimes use water, but they often fight fire with fire! They do that by lighting what are called "backfires," which are small, controlled fires that burn up fuel in the path of large wildfires. That way, when the wildfire gets there, it has nothing to burn and nowhere to go, because all the burnable fuel has already gone up in smoke. The Hotshots also clear away fuel using old-fashioned hard work. For example, they use a saw to cut away trees and heavy brush that could catch fire. Of course there are times when the Golden Eagles Hotshots do have trucks to supply water to the fires. But the water is limited, and these guys have to rely on hard work more than anything. Physical fitness is very important. They have to be in great physical shape to handle steep hills and difficult terrain  while carrying a 60-pound pack. The Golden Eagles Hotshots definitely work hard for their pay. But thanks to their efforts, many lives have been saved, many houses have not burned, and countless trees are still standing. 68. According to the passage, why do the firefighters light "backfires"?
To signal for help. To remove obstacles. To protect trees and bushes. To prevent the fire from spreading.