Final answer:
Cuba is the country that has the Cauto River and the Toa River, whereas the region of Mesopotamia and the Iguazú Falls are located in South America, on the border of Brazil and Argentina.
Step-by-step explanation:
The country that has both the Cauto River and the Toa River is Cuba. These rivers are significant watercourses within Cuba, with the Cauto River being the longest in the country. However, the mentioned Mesopotamia region which contains the Iguazu Falls, lies between the Parana and the Uruguay Rivers and is located in South America, significantly far from Cuba.
The Iguazu Falls, bordering Brazil and Argentina, should not be confused with any river or location in Cuba. The Iguazu Falls is known for its expansive series of waterfalls and serves as a major tourist attraction with its spectacular views and powerful flow.