Which of the following drug is an example of psychological antagonism

Physiological antagonism describes the behavior of a substance that produces effects counteracting those of another substance (a result similar to that produced by an antagonist blocking the action of an agonist at the same receptor) using a mechanism that does not involve binding to the same receptor. Prostacyclin (PGI(2)) is a potent endogenous inhibitor of platelet function and possesses a strong vasodilator effect. Fuhermore, prostacyclin is currently presented as the physiologic antagonist of thromboxane Ref-KDT 7/e p58