How was Darius able to maintain control of such a large empire select the two, correct

He forced providences to pay tributes they were unable to afford
He gave local rulers some control over their government
He established a different currency for each of the providence
He adapted a monotheistic religion
He funded the construction of empires

The correct answers are:

1. He forced provinces to pay tributes they were unable to afford.
2. He gave local rulers some control over their government.