John purchased a wood chipper from Garden Supply. The wood chipper had been defectively manufactured by Big Tractor. Under the law of his state, John may not sue Big Tractor, who was responsible for the defect, only Garden Supply who sold it to him. John's state follows the common law doctrine of:

A. Horizontal privity of contract

B. Vertical privity of contract

C. Caveat emptor

D. Respondeat superior