Final answer:
Tobacco was the product that made the Chesapeake Bay colonies economically viable, leading to the establishment of a plantation economy reliant on enslaved labor.
Step-by-step explanation:
The product that enabled the Chesapeake Bay colonies to become economically viable was tobacco. Initially, early Virginians at Jamestown sought precious metals, but it soon became evident that tobacco production was the most reliable source of income. In Maryland, George Calvert, the first Lord Baltimore, aimed to create a colony with a favorable climate for tobacco cultivation, an ambition realized by his son through the Maryland charter. Tobacco's labor-intensive cultivation required a substantial workforce and led to the development of plantations and the use of enslaved labor. The success of tobacco as a cash crop made it the most lucrative product of the Chesapeake colonies.