Final answer:
The efforts to save bald eagles from extinction eventually succeeded thanks to protections under the Endangered Species Act.
Step-by-step explanation:
The piece of evidence that best supports the idea that the efforts to save bald eagles from extinction eventually succeeded is the statement:
Thanks to protections under the Endangered Species Act, the bald eagle began a slow comeback...
This evidence highlights that the protections provided under the Endangered Species Act were effective in allowing the bald eagle population to recover. The Endangered Species Act, enacted in 1973, requires the U.S. Fish & Wildlife Service to develop management plans to protect listed species and bring them back to sustainable numbers. This act played a significant role in the conservation of the bald eagle population, leading to its successful recovery.