52. Tammy and Joe exchanged office buildings. Tammy's building had an adjusted basis of $140,000 and a FMV of $160,000. Joe's building had an adjusted basis of $130,000 and a FMV of $170,000. In addition, Tammy's mortgage of $50,000 was assumed by Joe and Joe's mortgage of $60,000 was assumed by Tammy. What is Joe's recognized gain? Select one: a. $50,000 b. $10,000 c. $0 d. $40,000