I would make a law where anyone can come over to the United States and stay, regardless of their legal status. Open borders, where anyone, from anywhere, can, in exchange for providing ID, a customs/smuggling/invasive species check of their belongings, and maybe a health check, they get in. Once in, a separate but similarly simple process to get a green card. Following a suitable period of residency, say, 5-10 years, citezinship (if they want it). It would be suitable for this law to fall under the Legislative Branch, as it makes all laws (including laws relating to immigration), declares war, regulates interstate and foerign commerce, and controls taxing and spending policies.
I think that it is the Atlantic but let me know if this is incorrect...
An advantage of separation of powers includes no one branch being able to control the entire agenda, preventing monarchy.
Answer:
A century.
Explanation:
I say a century because we can automatically knock out forever and a millennia because resources can not last forever and 1000 years (a millennia) just isn't reasonable.
10 years is just too short, even with the current consumption per year
If I'm wrong then it would be 10 years. Around 50 years would be the most correct answer but you don't have that choice.
Good luck!