Johnson Construction Corporation ordered 450 door units for an apartment condominium project from Billboe Lumber Corporation. The doors were delivered to the job site three weeks after they were ordered. Each door unit came wrapped in clear plastic. Five and one-half months after receiving the door units, Johnson Construction notified Billboe Lumber that the doors were one-quarter inch off size. Johnson refused to pay Billboe Lumber the balance due. What rule of law may Billboe Lumber use to recover the money owed?