The correct answer is manufacture products.
The system of mercantilism was used by Great Britain while they were in control of the North American colonies. This system relied on Great Britain having a favorable balance of trade, gaining natural resources from the colonies, and develop products that could benefit the British economy. Many of the resources supplied by the North American colonies would be sent to Great Britain to be turned into manufactured goods and then sent back to the colonies for sale.
Essentially, the colonies existed to benefit the "mother country" (aka Great Britain's) economy.