Question

By the late twelfth century, what economic activity replaced agriculture as the most dynamic force in the European economy?

bartering
banking
trade
industrialization

Answer 1

It should be trade, as at that time cities like Venice and Genoa first start to emerge as important trading hubs. 

Answer 2

Although normally seen as a time of decay and isolationism, the Middle Ages and mostly the 12th and 13th centuries were a period of great economic development, the increase of production resulted from feudalism led to a renewal of trade not known to western Europe since roman times. Specially in Italy, where the urban population reached 20% in the 12th century, the highest urban rate of the time, and huge cities such as Venice, Milan and Florence took the lead of the commercial revolution.