CHAPTER 18 ETHICS TODAY! WHEN IS IMPOSSIBILITY OF PERFORMANCE A VALID DEFENSE.? Rural Holding A.. contracts with Sweetwater Homes to sell real property that, unknown to either party, has groundwater contaminated from adjacent and occupied several decades carlier by Toxic Products Inc. When this is discovered, Rural anerts the doctrine of commercial impracticability. This doctrine applies only whet, with respect to an event that rendere performance impossible at the time the contract was formed the parties a could not have reasonably foreseen the supervening event. O b.should not have foreseen any supervening events O should have foreseen the supervening event reasonable or tot Od could have reasonably foreseen the supervening event