The correct answer is - a decrease in population.
During the 1300's the economic production in Europe had experienced a significant decline and this is due to the significant decrease in population. The decrease of population was cause by the emidemy of the plague that stroke the continent and millions of people died by the so called ''black death''. The plague was literary transported (unintentionally) through the trading roots of the Mongol Empire where trade was going on constantly between the European and Asian continents.
