Why Did Trade Not Play a Big Role in the Incan Economy? asap

Trade was not an important pillar in the economy of the Incas, mainly due to the geographical isolation of the Inca Empire from other important native nations, such as the Mayas, Aztecs or Olmecs, who were much further north, and even from other closer nations such as the Guaranies or the Amazonian aborigines, as they were separated by the Andes Mountains. Therefore, there was no commercial relationship between the Incas and other native nations.

answer; /// i believe that the correct answer is (d)the huang he river valley;