Choice "A" is correct. An action for strict product liability will succeed only if the product was in a defective condition when sold, the seller was in the business of selling goods, the defect caused the plaintiff's injury, and the product was expected to and did reach the consumer without substantial change.
Choice "b" is incorrect. The seller need not have been aware of the defect.
Choice "c" is incorrect. Strict product liability extends to all foreseeable users, privity is not required.
Choice "d" is incorrect. The seller need not have failed to exercise due care; liability is strict and can be imposed even on a careful seller.