The correct answer is C) Athenians had helped Ionian cities when they revolted against the Persians.
Persian emperor Darius invaded Greece because "Athenians had helped Ionian cities when they revolted against the Persians."
The first Persian invasion started in 492 BC. King Darius of Persia was angry at Greece because Athens had helped the Ionian cities when they rebelled against the Persians. So, King Darius, that hated the Athenians, order Mardonius to lead the invasion. He captured Macedon and Thrace. Athenians and Persian armies fought bloody battles but in the end, the Athenians won the war when they were victorious at the Battle of Marathon in 490 BC.
The Crédit Mobilier scandal of 1872-1873 damaged the careers of several Gilded Age politicians. Major stockholders in the Union Pacific Railroad formed a company, the Crédit Mobilier of America, and gave it contracts to build the railroad. They sold or gave shares in this construction to influential congressmen.
Both the Roman and Han economies were in large part based on agriculture. Sea trade was less expensive than land trade and the fact that Rome was more of a naval empire than the Han Dynasty meant that commerce played a greater role in the Roman economy.
