Answer:
B. A unrealized holding loss of $10 million in 2022.
Step-by-step explanation:
By December 31, 2021, the bonds were worth $150 million, resulting in an $18 million unrealized gain. By the time the bonds were sold, their price had deceased to $140 million, which means that $10 million of the $18 million previous gain had been erased. Therefore, the adjusting entry on December 31, 2022, should include the $10 million unrealized loss.