What are ways to address the progressive-regressive tax dilemma?

Why would nations in latin america be part of a mostly arab cartel group known as opec? a) latin america refused to do business with countries that were not part of opec. eliminate b) natural resources such as oil are a major economic development for some latin american countries. c) latin america has a long history of distrust of the united states and fears a take-over of oil fields. d) latin american nations such as venezuela needed in getting natural resources to other parts of the world. 15