The correct answer is A. troposphere.
The troposphere is the lowest layer of Earth’s atmosphere. It extends from the surface of the Earth to an average height of about 12 kilometers (7.5 miles). The troposphere is where most of Earth’s weather occurs. The temperature in the troposphere decreases with increasing altitude. This is because the air in the troposphere is heated by the Earth’s surface. The Earth’s surface absorbs energy from the sun and re-emits it as heat. This heat warms the air in the troposphere. The air in the troposphere is also heated by the condensation of water vapor. When water vapor condenses, it releases heat. This heat warms the air in the troposphere.
The troposphere is divided into three sublayers: the planetary boundary layer, the lower troposphere, and the upper troposphere. The planetary boundary layer is the layer of air closest to the Earth’s surface. It is the layer of air that is affected by the Earth’s surface. The lower troposphere is the layer of air above the planetary boundary layer. It is the layer of air where most of Earth’s weather occurs. The upper troposphere is the layer of air above the lower troposphere. It is the layer of air where the temperature decreases most rapidly with increasing altitude.
The troposphere is a very important layer of Earth’s atmosphere. It is the layer of air where we live and breathe. It is also the layer of air where most of Earth’s weather occurs. The troposphere is a very dynamic layer of Earth’s atmosphere. The temperature, pressure, and humidity in the troposphere can change rapidly. This is why we often experience changes in weather in the troposphere.
The other options are incorrect because they are not the main atmospheric layer near the surface of Earth. The mesosphere is the layer of Earth’s atmosphere above the stratosphere and below the thermosphere. The ionosphere is a region of Earth’s atmosphere that is ionized by solar radiation. The stratosphere is the layer of Earth’s atmosphere above the troposphere and below the mesosphere.