Explicar las diferentes dificultades económicas que España tenía en el intercambio con sus colonias americanas hacia fines del S. XVIII

How were the okanogan highlands formed? a. by subduction, which caused huge folds in earths surface b. as a result of retreating glaciers carving great valleys into the earth c. when molten rock from under the earth approached the surface d. when the collision of volcanic island chains and ocean rocks formed new earth