Final answer:
Neal must recognize a $30,000 gain on the sale of his interest in the house.
Step-by-step explanation:
The correct statement is:
b. Neal must recognize a $30,000 [$50,000 - 1/2($40,000)] gain on the sale of his interest in the house.
Under the divorce agreement, Ella receives the house and makes annual payments to Neal. This means that Neal is transferring his interest in the house to Ella. Since Neal's basis in the house is $40,000, and the value of his interest in the house is $50,000, he must recognize a gain of $10,000 ($50,000 - $40,000) on the transfer.