The correct answer is: gold and silver.
Mercantislism was an international economic policy approach which consisting on maximizing a country's exports. It was specially popular in the 16th-18th centuries. It is considered one of the forces that motivated European countries to colonize territories.
The wealth of the countries was measured in terms of the amount of precious metals they had in their balance. If the amounts of gold and sirver were large, these evidenced that the values of the country's exports had exceeded those of its imports.
Cheap raw materials from its colonies, allowed a country to produce at a low cost and then to sell manufactured exports at higher prices in the international markets.