Which South American country's economy is based on both agriculture and petroleum production?

Venezuela's economy is significantly influenced by both agriculture and petroleum production, making it a prime example in relation to the question. Historically, Venezuela has been one of the world's largest exporters of oil, with petroleum accounting for a substantial portion of its GDP and government revenue. While agriculture does play a role in its economy, particularly in the production of crops such as coffee and various vegetables, the impact of oil extraction and refinement is even more pronounced. This dual reliance on agriculture and petroleum highlights the country's economic structure.

In contrast, other South American countries mentioned have economies that, while also incorporating agriculture and petroleum, do not depend on oil production to the same extent as Venezuela. For instance, while Brazil has a diverse economy with significant agricultural exports such as soybeans and sugar, it does not have oil as its primary economic driver. Colombia has a robust agricultural sector but its petroleum industry isn't as dominant as Venezuela's. Ecuador also produces oil, but its economy is more heavily reliant on agriculture compared to that of Venezuela. Thus, the unique emphasis on both agriculture and a leading petroleum industry in Venezuela makes it the correct answer.