Which of the following is the best example of Agreement between OligopolistsSelect one:a.GATTb.OPECc.WTOd.UNIDO

The best example of Agreement between Oligopolists from the given options is OPEC.

OPEC, or the Organization of the Petroleum Exporting Countries, is a group of 14 nations that together account for around 44 percent of the world's oil production and 81.5 percent of the world's oil reserves. They work together to coordinate and unify petroleum policies, ensuring the stabilization of oil markets in order to secure an efficient, economic, and regular supply of petroleum to consumers.

This is a classic example of oligopoly, where a small number of firms have the large majority of market share. The member countries of OPEC have a significant influence on the price of oil globally by increasing or decreasing their oil production. Therefore, their agreement to coordinate policies is an example of agreement between oligopolists.