Which of the following layers of the atmosphere is the closest to space?

The layer of the atmosphere that is closest to space is the Thermosphere. The Thermosphere is the outermost layer of the atmosphere and extends from about 80 kilometers (50 miles) to several hundred kilometers above the Earth's surface. It is called the Thermosphere because the temperature increases with altitude in this layer. The Thermosphere is where the International Space Station and many other satellites orbit the Earth.