Which of the following was not developed until the early part of the twentieth century

The earth's atmosphere has layers: the exosphere, thermosphere, mesosphere, stratosphere, and troposphere from highest to lowest levels.

These layers are composed of Nitrogen, oxygen, other gases and are defined by unique characteristics of temperature and pressure.

1. Path A (Atmosphere)

The carbon path in this layer involves atmospheric carbon dioxide. The burning of fossil fuels like petrol, coal, diesel, volcanic explosions and wildfires brings back the carbon dioxide in the atmosphere during these processes.

2. Path G (Geosphere)

The carbon path involves the lithosphere. Expiration by plant and animal, burning of carbonate rocks like limestone, shale gas and coal release carbon which get backs in the atmosphere.

3. Path H (Hydrosphere)

The carbon path involves oceanic carbon dioxide. Ocean and water bodies have enormous amounts of dissolved carbon in them. Aquatic plants use this diffused carbon dioxide and free it back into the atmosphere.

To learn more about the atmospheric layers of the Earth follow the given link:

link