Final answer:
The early sea explorers were in search of the fabled c) Northwest Passage, an all-water route across North America, to expedite trade with Asia.
Step-by-step explanation:
Early sea explorers were looking to find the fabled Northwest Passage, an all-water route across North America. The correct answer to the question is c) Northwest Passage.
This was a mythical route that European and American explorers hoped would allow for a quicker passage to the Pacific Ocean and facilitate trade with Asia, therefore it was highly sought after.
Explorers searched for this water route for years, including the expedition of Lewis and Clark commissioned by the U.S. government and earlier voyages by explorers like Henry Hudson. However, despite many attempts, the reality was that such a passage did not exist due to geographic and climatic barriers.