Global Change in the earth system Part 4

Our planet is shaped by a variety of cyclic changes that happen over and over (sometimes with different results) and unidirectional changes that involve changes that are unlikely to repeat. Which events represent examples of unidirectional change?

Choose one or more:
A. movement of carbon through Earth's reservoirs
B. evolution of life
C. growth and demise of supercontinents
D. sea-level changes
E. development of a nitrogen and oxygen-rich atmosphere
F. differentiation of the Earth's interior