What are the 5 subgroups of geologic time scale?

Which of the following is a testable hypotheses?

Which of the following is likely not involved in this example of ecological succession? a) the rotting remains of plants add to the fertility of the soil. b)the soil becomes so fertile that eel grass is replaced by other plant species. c) the roots from plants stabilize the sediment, keeping it in place. d) the concentration of salt becomes so high that all plant life is destroyed.

How can we use spectral lines of light coming from the superclusters to identify which is receding from earth at the slowest rate.