What describes the Rio de la Plata

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Explanation:

Rio de la Plata is the muddy estuary of the Paraná and Uruguay Rivers, and forms part of the border between Argentina and Uruguay. The rich estuary supports both capital cities of Buenos Aires and Montevideo. The Paraná is South America's second longest river, and drains much of the southeastern part of the continent

it was created as a proprietorship, unlike any other colony.

explanation:

did it already

the answers is b.   environments.