Among the main reasons for the fall of the western roman empire was
a. the flooding of the market with gold and silver.
b. pressure on the empire's frontiers by tribes of barbarians.
c. the loss of manufacturing to competitors who charged less than the romans for their goods.
d. invasions led by emperors of the eastern roman empire who were jealous of the west's wealth.

B. Because even with many issues that plagued the Roman Empire economically and politically, By the later years of the empire the Roman military was mainly comprised of trained Barbarian soliders who were inferior to earlier Roman soliders causing a significant decrease in the Roman Empires's Military capablities so many barbarian tribes that began to grow such as the Huns, Vandals, Goth etc. Put immense pressure on the Empire, driving them into the ground economically and causing many issues within the government and eventually being sacked, thus marking the end of the Roman Empire. Sorry for the wall of text but hope this helped :)