Final answer:
Brazil is the South American country that borders all other South American countries except for Ecuador and Chile.
Step-by-step explanation:
The country that borders all South American countries except Ecuador and Chile is Brazil.
Brazil shares its borders with Argentina, Bolivia, Colombia, Guyana, Paraguay, Peru, Suriname, Uruguay, and Venezuela.
This makes it the country with the most land borders in South America, touching every country on the continent except for Ecuador and Chile.