Which of the following situations involving an exchange of business property does NOT exemplify a fully nontaxable exchange?

a. David traded his delivery van with Marcia for a delivery van that had more space and less mileage. He also paid her $2000 in cash

b. Miranda traded a commercial building plus $50,000 for Patricia's commercial building.

c. Harold traded an improved lot for Oliver's rental house. Oliver paid the $2,000 expense incurred with the exchange.

d. Sarah traded a fully leased office building for an office building that did not have any tenants. No cash or expenses incurred for the exchange.