On May 6,Robbie Entered into a Signed Contract with Ed,whereby

On May 6,Robbie entered into a signed contract with Ed,whereby Robbie was to sell Ed a painting having a fair market value of $350,000 for $130,000.Robbie believed the painting was worth only $130,000.Unknown to either party,the painting had been destroyed by fire on May 4.If Ed sues Robbie for breach of contract,Robbie's best defense is:

A) risk of loss had passed to Ed.
B) lack of adequate consideration.
C) mutual mistake.
D) unconscionability.