The expansion and stability of the inca empire was aided by
a) the widespread use of horses for quick communication.
b) the aztec policy of swift punishment to stop rebellions.
c) an extensive network of roads that linked its territories.
d) its alliance with the spanish conquistador francisco pizarro.

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 conquistadores. 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.