15. On September 25 of the current year, Bob sold machinery (AB $4,000; AD $8,000) for a total price of $20,000. Payments are to be made in four annual installments beginning immediately. What is the amount and character of gain to be recognized by Bob this year because of the sale? a. $8,000 Sec. 1245 gain and $2,000 Sec. 1231 gain. b. $8,000 Sec. 1245 gain and $4,000 Sec. 1231 gain. c. $4,000 Sec. 1245 gain and $ 0 Sec. 1231 gain. d. $8,000 Sec. 1245 gain and $8,000 Sec. 1231 gain. e. None of the answers provided is correct