Answer:
The number of years they serve per term.
Castner Cutthroat i think
We are what makes the earth. Our actions are what shapes the world and yourself. For an example: If everyone recycled we could reuse certain materials and make the earth less polluted. It's up to you to have the future of your planet be the way you want it to be.
I really wish you provided the research study. I would be happy to answer. It should be attached to wherever you found this question. Hope this helps :)