Read the passage below carefully, and then choose the best answer:
Flying Drones into Danger Zones
A plane is sent deep into the enemy territory with a deadly mission. It is assigned to eliminate several key targets with a precision bombing campaign. This mission won’t be easy, however, as to be successful, the plane will have to avoid enemy rockets and tank fire. There will be no risk to the life of the “pilot” of the plane because he will not be able to aboard the vessel. Instead, he will be thousands of miles away inside a control tower, as he is operating a drone. Drones, which are also called UVAs or unmanned aerial vehicles, marked a major step forward in technology. Inventors have been working on them since the early 1900s. Although some devices were designed back then, they weren’t able to do much more than a standard model airplane. In fact, it was not until a US plane was shot down in 1959 during the Cold War that the US military really got serious about drones. The aim was to save pilots’ lives while flying over hazardous territories. Drones usually fall into two categories. The first type of drones relies on human control from a remote location. The second type of drones is preprogrammed with computer instructions, and it then completes its mission operating autonomously. In addition to protecting pilots’ lives, drones also have several other advantages. They can stay in the air for longer periods of time because there is no concern for eating, sleeping, or rest breaks that pilots typically require. Drones can also be produced cheaper since manufacturers don’t need to value safety precautions as they would for aircraft flown by humans. Despite their usefulness, military drones have been the cause of great criticism over the past decade. There have been cases of British and American drones missing their targets and killing innocent civilians instead. The Brookings Institution released a statistic that for every military leader who is killed by a drone strike, ten civilians die. Some suggest that if human pilots were flying these planes, they wouldn’t have made these errors. Drones don’t always have targets that they must eliminate. The military also employs special surveillance drones that use long-range cameras to gather information about buildings, enemy soldier formations, and other vital information from the ground. In the end, whether people are for or against the use of drones, it appears that they are certain here to stay.
4. What is an advantage that drones have over normal planes?