The only place you'd find a marmoset in what gold rush region would be in a zoo?
Options:
- in wild
- your moms house
- burrow
- american west
- national park
Let's think now! Step-by-step reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
American west areas have zoo. American west areas are gold rush regions in zoo.s.
So, the final answer is american west.