Among the countries listed, Liberia is the one that took direct inspiration from the U.S. Constitution and Bill of Rights. Founded in the early 19th century by freed American slaves, Liberia adopted similar democratic principles and legal frameworks drawn from the U.S. system.
While both France and Spain have democratic systems, their historical contexts and constitutional frameworks were influenced by a variety of sources, and they do not have the same direct ties to the U.S. Constitution as Liberia. El Salvador has faced significant challenges in its democratic process, although it has made strides toward democracy over the years.
So the country that fits the criteria in your question is Liberia.