George's Greenery orders two dozen live dogwood trees from Nancy's Nursery. George's is to keep the dogwoods healthy by keeping them in a greenhouse following certain instructions to keep the air at the right temperature, etc. The sale is made on a trial basis and George's may return all unsold dogwood trees at the end of 30 days. This contract is a: Select one: a. Sale or return b. Conditional sale c. Contract to sell future goods d. Sale on approval