Concept:A cartel is an organisation of independent producers in the same industry who join together to control supply and fix prices.Explanation:The question describes producers of similar goods who combine to control output.Their main aim is to fix prices and reduce competition.This is exactly the feature of a cartel.A trust is controlled by a central board, while a syndicate or consortium is usually formed for joint projects, not for fixing prices.Therefore, the correct option is cartel.Answer:D. cartel