Which of the following countries forms part of the Amazon River basin?

Concept

A drainage basin is the entire land area from which a river and its tributaries collect water.

A country forms part of a river basin if any part of its territory drains through that river system; the main river need not cross the country.

Application

Venezuela qualifies because a small area in its south drains into the Rio Negro, an Amazon tributary, through the Casiquiare–Rio Negro system.

Contrast

• Argentina: its major northern river network belongs to the Paraná–Paraguay–Uruguay system and the Río de la Plata basin.

• Chile: its territory lies west of the Andes, and its rivers generally drain directly to the Pacific Ocean.

• Venezuela: its southern drainage includes the Casiquiare connection to the Rio Negro and thus to the Amazon system.

• More than one of the above: this would require at least two of Argentina, Chile, and Venezuela to contain Amazon-basin drainage.

• None of the above: this would require all three named countries to lie outside Amazon-basin drainage.

Cross-check

Standard basin-country maps include Venezuela but exclude Argentina and Chile. Therefore, among the offered country names, Venezuela is the only one that forms part of the Amazon River basin.

Result

Venezuela