Not sure if this is multiple choice but this is what I say.
Wind, composition of the tombstone and the PH level f any moisture that may come in contact with the tombstone.
Hope this helps if I'm not too late :)
Solar power because it is never ending and has no emmisions
The term matabolism is based on Greek word that means "change". ... Because metabolism is the action of how fast an organism changes nutrients into useful chemicals and elements for the organism to grow.
-Mabel <3
Temperature. Amounts of water available. Just to name a few