Final answer:
The Sturgeon returned to the St. Louis River, a tributary of Lake Superior, indicating the correct answer is D) Lake Superior.
Step-by-step explanation:
The Sturgeon has returned to the St. Louis River, which is the largest tributary of Lake Superior, making the correct answer to the question D) Lake Superior. The St. Louis River flows into Lake Superior, which is the northernmost and westernmost of the Great Lakes and is the largest freshwater lake by surface area in the world. The return of the sturgeon to the river is significant from both an environmental and conservational perspective, indicating the success of efforts to revitalize the habitats in and around the Great Lakes. It's important to remember that proper management of waterways and preventing the spread of invasive species like the Asian carp is crucial for maintaining the health of native aquatic populations.