The correct answer is (b), Mesosphere.
The mesosphere is the fourth layer of Earth’s atmosphere, above the stratosphere and below the thermosphere. It extends from about 50 to 80 kilometers (31 to 50 miles) above Earth’s surface. The mesosphere is the coldest layer of Earth’s atmosphere, with temperatures as low as -90 degrees Celsius (-130 degrees Fahrenheit).
The mesosphere is cold because it is far from Earth’s surface, where the Sun’s heat is strongest. The mesosphere is also thin, with only about 0.01% of Earth’s atmosphere. This means that there is less air to trap heat from the Sun.
The mesosphere is important because it protects Earth from meteoroids. Meteoroids are small pieces of rock or metal that orbit the Sun. When a meteoroid enters Earth’s atmosphere, it heats up and glows. This is what we see as a shooting star. Most meteoroids burn up in the mesosphere, but some larger ones can make it to the ground.
The mesosphere is also important for radio communications. Radio waves can travel through the mesosphere, which allows us to communicate with satellites and other objects in space.
The other options are incorrect because:
- The stratosphere is the second layer of Earth’s atmosphere, above the troposphere and below the mesosphere. It extends from about 12 to 50 kilometers (7.5 to 31 miles) above Earth’s surface. The stratosphere is warm because it contains ozone, which absorbs ultraviolet radiation from the Sun.
- The thermosphere is the outermost layer of Earth’s atmosphere, above the mesosphere. It extends from about 80 to 600 kilometers (50 to 373 miles) above Earth’s surface. The thermosphere is hot because it is exposed to direct sunlight.
- The troposphere is the lowest layer of Earth’s atmosphere, extending from Earth’s surface to about 12 kilometers (7.5 miles). The troposphere is warm because it contains water vapor, which absorbs heat from the Sun.