Answer:
C. Kantian ethics
Explanation:
Immanuel Kant's ethics considers the well being as the true good. The action's goal underlies to follow universal moral qualms. This makes the persons act above their interests and wishes.
In this case, Portman feels the duty to perform the contract, even as it is against their interest (the new suppliers charges more) because; Portman is acting in well-being we stablish it is following Kantian ethics