The correct option is B Mesosphere
Mesosphere is the layer of the Earth's atmosphere that is directly above the stratopause and directly below the mesopause. In the mesosphere temperature decreases with increasing height.
The main dynamic features in this region are strong zonal (East-West) winds, atmospheric tides, internal atmospheric gravity wavesand planetary waves. Most of these tides and waves are excited in the troposphere and lower stratosphere, and propagate upward to the mesosphere. In the mesosphere, gravity-wave amplitudes can become so large that the waves become unstable and dissipate.