Answer: C) an extensive network of roads that linked its territories.
The Inca Empire was the largest empire of South America and one of the most advanced in pre-Columbian America. The centre of the empire was located in Cusco, modern Peru. The empire was conquered in its totality by 1572. One of the main factors that contributed to its success was its extensive network of roads.
Incas (or any other American people) did not have horses, which only arrived with the European <em>conquistadores</em>. Moreover, they did not have any contact with the Aztec people of central Mexico. Finally, the Incan empire faced its decline with the arrival of Francisco Pizarro.
The Americans implemented the Articles of Confederation as the first form of constitution. However, this document established a very weak form of government.