Correct Option
The correct option is Thermosphere.
Explanation
The Earth's atmosphere is divided into five distinct concentric layers based on temperature variations and composition. In ascending order from the surface, these are the Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.
Detailed Analysis
- Thermosphere: This layer extends from the Mesopause (approximately 80 km altitude) up to the base of the Exosphere (approximately 400-600 km). Therefore, it is the specific layer located between the Mesopause and the Exosphere. The Ionosphere is a sub-region within the Thermosphere characterized by the ionization of atoms.
- Troposphere: This is the lowermost layer of the atmosphere, extending from the surface up to the Tropopause.
- Stratosphere: This layer lies above the Troposphere and extends up to the Stratopause. It contains the ozone layer.
- Ozonosphere: This is not a distinct primary layer in the thermal classification but refers to the ozone-rich region largely contained within the Stratosphere.
Key Takeaway: The vertical sequence of atmospheric layers is Troposphere → Stratosphere → Mesosphere → Thermosphere → Exosphere. The Thermosphere lies directly above the Mesopause and below the Exosphere.