"I am quite certain that . . . (Rome) would never have been able to be so great had not the immortal gods been placated." –Cicero, from The Nature of the Gods According to Cicero, what was the reason why Rome was so great?

Responses :
The government adopted Judaism.
They believed in only one god.
The government was a republic.
They had made the gods happy.

According to Cicero, the reason why Rome was so great was because they had made the gods happy.