Answer :
According to Henry Clay, the key to uniting the United States was a strong American economy that protected both industrial and agricultural interests.
What did Henry Clay believe?
Henry Clay believed that in order to unite the United States, the U.S. economy had to be strong. Tariffs were also needed to protect the industrial section of America.
He also believed that agriculture needed to be invested in by developing profitable markets for it.
In conclusion, option A is correct.
Find out more on Henry Clay at https://brainly.com/question/535050.