$12$ Identify the trade$-$restraining practice that this example demonstrates.

The CEOs of two pharmaceutical companies are having lunch. They discuss the unfair costs of ordering from a manufacturer that supplies to both companies. The CEOs decide that they will no longer work with the unfair pricing of the manufacturer.

$\backslash$table$[[$Controlling output$],[$No illegal practice$],[$Price fixing$],[$Illegal boycott$]]$