I would say C: <span>Greece regrouped and conquered the Roman Empire. Because that's literally what the phrase says; she conquered us. Really the most logical reason.</span>
The correct answer is obscene material.
Letter D is represented by the Danube river because it goes through the borders of all of the countries: Germany, Austria, Hungary, Slovakia, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine.
Filial piety in Confucius is the virtue of respecting your elders and ancestors.