The correct answer among all the other choices is C. The feuds between religious and secular power over investiture. The fall of the western Roman empire contributed most directly to this circumstance. Thank you for posting your question. I hope that this answer helped you. Let me know if you need more help.
In English speaking jurisdictions the Square and Compasses are often depicted with the letter "G" in the center. The letter is interpreted to represent different words jurisdiction to jurisdiction. Among the most widely accepted interpretations are that: [G] stands for God, and is to remind Masons that God is at the center of Freemasonry. In this context it can also stand for Great Architect of the Universe (a reference to God). In a different context, the letter stands for Geometry, described as being the "noblest of sciences", and "the basis upon which the superstructure of Freemasonry is erected."[3]
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 :)