The decline of both the Han Dynasty and the Roman Empire were a slow process. What of these factors was a catalyst for the decline of both these great powers? A. the use of mercenary soldiers to increase the size and strength of the military B. trade that depended on safe ocean travel for success C. heavy taxation of the lower classes, who could not afford to pay the high taxes demanded of them D. the emperor's decision to make himself an absolute leader whom his people must worship