Final answer:
William Abercrombie is best described as an explorer ordered to find a practical route from Cook Inlet to the Tanana River Valley, contributing to Alaska's infrastructure. The correct statement is first.
Step-by-step explanation:
- The statement that best describes William Abercrombie is that he was ordered to explore Cook Inlet and to find the most direct, practical route from tidewater to the Tanana River Valley.
- Abercrombie, a figure in the history of Alaska's exploration, is known for his role in exploring and mapping the region, as well as contributing to the construction of infrastructure in South Central Alaska.
- His efforts were part of a larger movement of exploration, colonization, and search for passages and resources, reminiscent of other historical endeavors like the search for the Northwest Passage or the exploration of the Pacific Ocean by the Corps of Discovery.