(d) An act or omission of a third party other than an employee or agent of the responsible party or a third party whose act or omission occurs in connection with any contractual relationship with the responsible party, except where the sole contractual arrangement arises in connection with carriage by rail,
provided that, to establish entitlement to any of the foregoing defenses, the responsible party shall plead and prove that the responsible party exercised due care with respect to the pollutant concerned, taking into consideration the characteristics of the pollutant and in light of all relevant facts and circumstances, and took precautions against foreseeable acts or omissions of others and the foreseeable consequences of those acts or omissions.