If an exam asks for the sequence involving Earth’s layers, the early atmosphere and the hydrosphere, which sequence is most accurate?

Correct answer: Layers by differentiation, atmosphere by outgassing, hydrosphere by cooling and condensation

The governing concept is the sequence of major processes in Earth’s early evolution. As the young Earth differentiated, dense materials moved inward and lighter materials formed outer layers, producing an internal structure. Volcanic outgassing released gases and helped establish the early atmosphere. Later, cooling lowered temperatures; water vapour condensed and accumulated, contributing to the hydrosphere. Thus option A correctly pairs each sphere with its process and order. The other choices confuse astronomical observations, rivers, soil, monsoon circulation or biological life with planetary formation processes, so they cannot explain the required sequence.