Lenny makes K2, a synthetic form of marijuana, in his basement. He signs an agreement with the Super Smoke Shop to deliver 1,000 cans of K2 for $10,000. After the contract is signed, but before the delivery, Super Smoke Shop's state legislature makes the sale of K2 illegal. Lenny's contract will be discharged because of ____? a. true impossibility b. commercial impracticability c. frustration of purpose d. none of these