Final answer:
The Anti-Imperialist League opposed imperialism and advocated for non-intervention.
Step-by-step explanation:
The stance of the Anti-Imperialist League can be best explained as opposing imperialism and advocating for non-intervention. The league, formed in 1898, consisted of diverse and prominent Americans who were against the idea of American empire building. They believed that empire building went against the principles of democracy and freedom on which the country was founded. While their reasons varied, the league presented a formidable challenge to the expansionist policies.