I believe that the correct answer would be Radioactive Dating of each layer because it give a precise age based on the amount of radioactive decay the rock releases over time
I hope this helps you; please let me know
I am not sure about the second one, but I know the first one.
The answer is D.
"An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure."
I'd say the answer is C Increase in plant and animal diversity.
Because grasslands are usually too dry for certain plants and animals to live there, but with more precipitation more organisms would live there.
d. the condition of the conducting system.