grace died in a car accident. the doctors reported that immediately prior to the accident she suffered a stroke causing her to lose control of her car which in turn led to the accident. assume that graces family was able to prove that the manufacturer of the car she was driving marketed the car knowledge of defect in its design the car was working properly at the time of the accodent despite the defect if graces family sued the manufacturer for negligence which of the following would most likely defeat the familys action