White sold his business to Phipps. As part of the sale contract, Phipps agreed to pay off a bill White owed to one of his suppliers. Assume that Phipps does not pay the supplier as called for in the contract. Which parties may file suit against him?

A. Either White or the supplier may sue Phipps, but not both

B. Only White may sue Phipps on the contract

C. Both White and the supplier may sue Phipps

D. Only the unpaid supplier may sue Phipps on the contract