Which of the founding fathers wrote in a letter to friend about the missouri compromise and the threat that the institution of slavery posed to the u. s.?
a. james madison
b. thomas jefferson
c. john adams
d. george washington

The Founding Fathers who wrote in a letter to friend about the Missouri Compromise and the threat that the institution of slavery posed to the U.S. was "C. John Adams", since Adams was generally against the institution of slavery.