In a federal court diversity action by Plant against Decord on an insurance claim, a question arose whether the court should apply a presumption that, where both husband and wife were killed in a common accident, the husband died last. Whether this presumption should be applied is to be determined according to 
traditional common law. federal statutory law. the law of the state whose substantive law is applied. the federal common law.
Question: In a federal court diversity action by Plant against Decord on an insurance claim, a question arose whether the court should apply a presumption that, where both husband and wife were killed in a common accident, the husband died last. Whether this presumption should be applied is to be determined according to 
A. traditional common law.
B. federal statutory law.
C. the law of the state whose substantive law is applied.
D. the federal common law.
Answer: