Which innovation promoted trade and contributed to the unity of the persian empire?

Use of standardized metal coins.

Explanation:

According to a different source, these are the options that are included with this question:

The use of standardized metal coins was the main innovation that allowed the Persian Empire to become more unified. As many people shared such coins, they began to see themselves as members of the same society. Moreover, these coins allowed trade to expand and become more efficient.

letter d is correct.

all of the following apply except for (a. excessive credit on real estate resulting in defaulted loans.

in 1819, panic swept the country due,in part, to the rapid expansion of american manufacturing during the war of 1812 and the distress caused by the post-war british competition. the rapid expansion of american farming was another factor.

explanation: