One of the Byzantine Empire's greatest contributions to civilization was Emperor Justinian's A.
preservation of Roman buildings.
B.
preservation of Roman republican government.
C.
preservation of traditional Roman customs.
D.
preservation of Roman law.

Justinian I served as emperor of the Byzantine Empire from 527 to 565. Justinian is best remembered for his work as a legislator and codifier. During his reign, Justinian reorganized the government of the Byzantine Empire and enacted several reforms to increase accountability and reduce corruption.

B.

preservation of Roman republican government.

the qing dynasty placed strict limits on foreign merchants' ability to trade in china.

the three answers (for plato at least) are:

b-condemned sola fida 

d-set rules for establishing seminaries and for educating clerics in the seminaries 

f-recommended moderation in the sale of indulgences and banned the sale of false indulgences