The best description of a key challenge faced by the early American republic after the Revolutionary War is:
The creation of a strong central government to address issues of state sovereignty and weak federal authority.
During this period, the Articles of Confederation created a weak central government, which resulted in difficulties in governing effectively, leading to issues such as economic instability and challenges in implementing laws. This challenge ultimately led to the Constitutional Convention of 1787 and the drafting of the U.S. Constitution aimed at creating a stronger federal government.